Authorities in Burundi say they have opened six mass graves containing more than 6,000 bodies from unrest that occurred decades ago, the largest such discovery in years of work.

The East African nation has been unearthing such graves from a past that includes massacres along ethnic lines. Some have warned that the work can be sensitive ahead of the presidential election in May.

The country's truth and reconciliation commission said the latest mass graves to be explored are in central Karusi province. There appear to be at least 18 such graves.

The province was plunged into crisis after the assassination in 1993 of Melchior Ndadaye, Burundi's first ethnic Hutu and democratically elected president. Some Burundians say ethnic Tutsi families were massacred after his death.

But the commission's president, Pierre Claver Ndayicariye, said the bodies were from 1972, when many ethnic Hutus were killed following a failed coup against leader Micombero Michel.

The people buried in the graves had been imprisoned and then taken in military trucks to the execution grounds, Ndayicariye said.

Some in Burundi have been critical of the commission's work and its choice of mass graves it chooses to investigate. Its mandate covers crimes committed between German colonization in 1885 to 2008 when the final rebel group signed a cease-fire agreement.

Emmanuel Nkurunziza, secretary of one Tutsi organization, called it "a shame to say thousands of thousands of dead bodies in Karusi are Hutus killed in 1972 while it is known that in 1993 Tutsis were exterminated in Karusi."

He added that "you cannot take Tutsis' bodies and call them Hutus."

In a statement on Monday, a coalition of political parties in exile said the commission should halt its work because it doesn't inspire confidence in all Burundians. The statement alleged that the commission was put in place to serve the interests of the ruling party.

Gunmen killed 24 men, including a church pastor, and kidnapped three others on Sunday in Burkina Faso, an official said. It was the latest attack against a religious leader in the increasingly unstable West African nation.

The mayor of Boundore commune, Sihanri Osangola Brigadie, said the attack occurred in the town of Pansy in Yagha province. The roughly 20 attackers separated men from women close to a Protestant church. At least 10 other people were injured.

"It hurt me when I saw the people," Brigadie said after visiting some of the victims in the hospital in Dori town, 180 kilometers (110 miles) from the attack. The gunmen looted oil and rice from shops and forced the three youth they kidnapped to help transport it on their motorbikes, he said.

Both Christians and Muslims were killed before the church was set on fire, said a government security official in Dori who spoke on condition of anonymity because they weren't authorized to speak to the media.

Attacks have targeted religious leaders in the area in the past. Last week, also in Yagha province, a retired pastor was killed and another pastor was abducted by gunmen, according to an internal security report for aid workers seen by The Associated Press.

Extremist violence has dramatically escalated in once-peaceful Burkina Faso. Analysts are concerned that attacks against civilians, including against Christians, are increasing "at an alarming rate," said Corinne Dufka, West Africa director for Human Rights Watch. "Perpetrators use victims' links to government or their faith to justify the killings, while others appear to be reprisal killings for killings by the government security forces," she said.

More than 1,300 civilians were killed in targeted attacks last year in Burkina Faso, more than seven times the previous year, according to Armed Conflict Location and Event Data Project, which collects and analyzes conflict information.

The insecurity has created a humanitarian crisis. More than 760,000 people are internally displaced, according to the government.

The National Electoral Board of Ethiopia (NEBE) announced on Friday it has fixed Aug. 29 for key national elections to elect parliamentary and regional assemblies' representatives.

NEBE had previously tentatively proposed the voting day to be Aug.10.

The announcement was made by Birukan Midkesa, Chairperson of NEBE during a discussion with various political parties, and civil society organizations.

Mideksa said the National Electoral Board of Ethiopia will work with the Ethiopia National Metrology Agency to mitigate the effects of the rainy season on the logistics holding the vote.

Ethiopia experiences annual rainy season from early June up to early September.

The last parliamentary and regional assemblies' elections were held in May 2015.

South Sudan's President Salva Kiir on Friday rejected any possible reduction in the current number of 32 states after consulting with local leaders in Juba.

Kiir said that his government is sticking to its earlier position of maintaining the 32 states or more states after failing to recently agree with Riek Machar, leader of the main-opposition group the Sudan People's Liberation Movement in Opposition (SPLM-IO) over the contentious issue in Ethiopia.

"What brought us here today is the issue of states, I brought this to you so that you decide, my brother Riek Machar and other non-South Sudanese who are living with the blood of South Sudanese people have different suggestions on the table, the government is saying 32 states plus Abyei," Kiir told local leaders during consultation meeting in Juba.

The SPLM-IO favors reverting to between ten states and 23 states.

"IGAD(Intergovernmental Authority on Development) and the international community said they need a lean government. We have reached a deadlock, that's why we came back for consultation. We were given six days until tomorrow (Saturday) we will take back what you will decide," said Kiir.

He also criticized foreign influence in the ongoing stalemate over the unresolved number of states issue with the opposition, adding some of these foreign players have shown bias during the talks.

"I have fought the so-called special envoys. They will tell us here something and go there to their heads of states with different information. There are people who stay with us and who have made South Sudan their own project for food, one day if we reach an agreement they will be jobless and this is what they don't want," said Kiir.

Deng Macham, head of South Sudan's council of traditional chiefs, said that South Sudanese people are comfortable with 32 states plus Abyei administrative area or even more.

He added that any decision to change the current status quo would unravel nascent peace gains by throwing the country back to conflict.

"We as traditional chiefs want to meet with the Inter-Governmental Authority on Development (IGAD) and Riek Machar to ask him why he wants to reduce the number of states, and where he is going to take the rest. We even need 37 states to leave alone those 32 people are talking about," said Macham.

Kiir on Wednesday said that he had made tactical withdrawal after the failed talks with Machar in Addis Ababa in order to consult with citizens.

The former warring parties are expected to return to the negotiating table in Addis Ababa on Feb.15.

Meanwhile, Machar has welcomed the East Africa bloc council of ministers recommendations of 10 or 23 states and not 32 as maintained by Kiir.

"We welcomed the recommendations of the Independent Boundaries Commission (IBC) of 10 states, the recommendations of the IGAD council of ministers of 10 or 23 plus one state (Abyei)  and the outcome of the tripartite summit of the three heads of state and government of 10 states," Machar said in a statement issued in Juba.

The IGAD heads of states during the regional body's 34th Extra-ordinary summit last week, accepted Juba's request to undertake further consultation on the number of states.

The issue remains the main contentious issue alongside security arrangements, which are delaying the formation of the much-awaited transitional unity government (TGoNU) slated for Saturday.

IGAD in its official communique released after the meeting said it recognized that the issue of the number of states and their boundaries is an internal South Sudanese matter and hence, solution should come from the South Sudanese people.

South Sudan descended into conflict in December 2013, after President Salva Kiir sacked his deputy Riek Machar leading to fighting between soldiers loyal to the respective leader.

The two leaders are currently implementing the 2018 revitalized peace agreement but have twice failed to form the unity government due to disagreement on the outstanding issues.

The oil industry in South Sudan has left a landscape pocked with hundreds of open waste pits, the water and soil contaminated with toxic chemicals and heavy metals, according to four environmental reports obtained by The Associated Press.

The reports also describe "alarming" birth defects, miscarriages and other health problems among residents of the region and soldiers who have been stationed there.

Abui Mou Kueth's infant son, Ping, was born with six fingers on both hands, one stunted leg, a deformed foot and kidney swelling.

"I was shocked the first time I saw the baby," she said, cradling him in her arms. "I am worried about his future."

The Associated Press obtained the reports and supporting documents from people with close knowledge of the oil operations, one of whom works in the industry. They've never been released publicly.

"South Sudan is running one of the dirtiest and poorest managed oil operations on the planet," said Egbert Wesselink, the former head of a European coalition of more than 50 non-profit organizations focused on the impacts of the country's oil sector.

"I don't think there's a single major industrial operation on earth that's getting away with this," he said.

There's been no clear link established between the pollution and the health problems.

But community leaders and lawmakers in the oil-rich areas in Upper Nile and Unity states accuse South Sudan's government and the two main oil consortiums, the Chinese-led Dar Petroleum Operating Co. and the Greater Pioneer Operating Co., of neglecting the issue and trying to silence those who have tried to expose the problem. An AP reporter was detained and questioned by government officials and government security forces working on behalf of the oil companies.

Neither company responded to multiple requests for comment on the reports, and did not answer detailed questions sent by email and text from AP.

The reports show that the government and the oil companies have been aware for years that contamination from drilling could be causing severe health problems, but little has been done to clean up the mess.

WASTE PITS, BIRTH DEFECTS

The oil rich area around Paloch, a city in Upper Nile state, is dotted with exposed pools of toxic water. A chemical junkyard in Gumry town, about 45 minutes from Paloch, was strewn with overflowing containers of black sludge that seeped into the ground and were surrounded by toxic waste, when an AP reporter visited in September 2018.

"We're losing children," said Nyaweir Ayik Monyuak, chairman of the Women's Association in Melut. The 43-year-old lost two children of her own between 2008 and 2011.

She and a dozen other women, crowded on a tattered L-shaped sofa in a dimly lit shed in Melut, told harrowing stories.

Six had lost babies in the last 10 years. And all of them knew someone who had struggled to conceive, had miscarriages or had given birth to a child with deformities such as stunted limbs or concave skulls.

THE STUDIES

The two earliest surveys were performed in 2013 and 2016 by South Sudan's government. They found oil pollution across the region and soil and water samples showed contamination, including mercury levels in the water were seven times what is permissible under U.S. Environmental Protection Agency standards.

Local residents reported increased miscarriages, stillbirths and incidents of "malformed newborn babies" that didn't survive, and soldiers stationed there were also falling ill.

In July 2018, Greater Pioneer - which is comprised of the state-owned China National Petroleum Corp., the Malaysian state-owned Petronas as well as South Sudanese and Indian drillers -- commissioned a study that found significant oil spillage and water pollution at the waste treatment facility at some oil operations that had been abandoned during the civil war.

A November 2018 report, commissioned by Dar Petroleum, found "extremely high" levels of hydrocarbons -- chemicals such as benzene that make up oil and natural gas and can cause serious health effects. It also documented 650 waste pits filled with water contaminated with arsenic and lead, and millions of liters of water contaminated with drilling chemicals sitting in ponds.

South Sudan's oil ministry instructed Dar Petroleum to move ahead with the proposed clean-up, according to a December 2018 letter seen by the AP.

But Dar Petroleum — a consortium that includes China's state-owned China National Petroleum and Sinopec, along with companies in Malaysia and Egypt and South Sudan's state-owned oil company — never acted, according to two people with close knowledge of the oil operations in the area who didn't want to be named for fear of their safety.

AP sent detailed questions to China National Petroleum Corp. and Sinopec, but neither company responded.

'PUBLIC HEALTH EMERGENCY'

There is no definitive proof that the pollution caused the health problems. South Sudan's crippling five-year civil war killed almost 400,000 people, displaced millions and plunged pockets of the country into famine.

But Rick Steiner, an oil pollution adviser in Alaska, said there is substantial medical literature linking hydrocarbon exposure with birth defects.

"The pollution is a public health and environmental emergency," he said.

South Sudan's petroleum minister, Awow Daniel Chuang, said until there's scientific evidence tying health problems to oil pollution, no conclusions should be drawn.

In July 2019, the Greater Pioneer Operating Company flew baby Ping and his parents to Nairobi, Kenya, and then to Berlin for what they thought would be medical treatment.

Ping's father, Cornelius Mayak Geer, says the company told him that they would first do tests to determine if Ping's deformities were tied to oil pollution. If they found a link, Geer says they told him, they would pay for treatment.

But the family returned from Berlin last month after loads of tests, but no treatment for the baby.

Geer said the company told him the child's problems were genetic, and not caused by oil pollution. But they never shared any test results with him.

"The baby still cries day and night because of the pain and not feeling well," he said. "They're just buying time until the baby dies.

Environmental experts say there is little incentive for multinational companies to do anything because it is easy to get away with things in impoverished countries like South Sudan.

Oil accounts for almost all the country's exports, according to the World Bank. And South Sudan is trying to revive its economy by expanding the industry.

"No one's really watching. The government is neither willing nor able to monitor and enforce its own environmental laws," said Luke Patey, senior researcher studying China's oil investments in Africa at the Danish Institute for International Studies.

He said the result is "a vicious cycle of negligence."