The United States and Saudi Arabia called on warring sides in Sudan to extend a cease-fire due to expire Monday.

The Sudanese army and a rival paramilitary force, battling for control of Sudan since mid-April, had agreed last week to the weeklong truce, brokered by the U.S. and the Saudis. However, the cease-fire, like others before it, did not stop the fighting in the capital of Khartoum and elsewhere in the country.

In a joint statement early Sunday, the U.S. and Saudi Arabia called for an extension of the current truce which expires at 9:45 p.m. local time Monday.

"While imperfect, an extension nonetheless will facilitate the delivery of urgently needed humanitarian assistance to the Sudanese people," the statement said.

The statement also urged Sudan's military government and the rival Rapid Support Forces to continue negotiations.

The fighting broke out in mid-April between the military and the powerful RSF. Both military chief Gen. Abdel-Fattah Burhan and RSF leader Gen. Mohammed Hamdan Dagalo led the 2021 coup that removed the Western-backed government of Prime Minister Abdalla Hamdok.

The fighting turned Khartoum and the adjacent city of Omdurman into a battleground. The clashes also spread elsewhere in the country, including the war-wracked Darfur region.

The conflict has killed hundreds of people, wounded thousands and pushed the country to near collapse. It forced more than 1.3 million out of their homes to safer areas inside Sudan, or to neighboring nations.

Residents reported renewed sporadic clashes Sunday in parts of Omdurman, where the army's aircraft were seen flying over the city. Fighting was also reported in al-Fasher, the provincial capital of North Darfur.

The U.S.-Saudi statement came two days after Burhan demanded in a letter to the U.N. secretary-general that the U.N. envoy to his country be removed, The U.N. chief was "shocked" by the letter, a spokesman said.

The envoy, Volker Perthes, has been a key mediator in Sudan, first during the country's fitful attempts to transition to democracy and then during efforts to end the current fighting.

Burhan's letter came after Perthes accused the warring parties of disregarding the laws of war by attacking homes, shops, places of worship and water and electricity installations.

In his briefing to the U.N. Security Council last week, Perthes blamed the leaders of the military and the RSF for the war, saying that they have chosen to "settle their unresolved conflict on the battlefield rather than at the table."