Former Malaysian Prime Minister Mahathir Mohamad, 97, was hospitalized Wednesday after testing positive for COVID-19, his office said.

“Mahathir has been admitted to the National Heart Institute for observation for a few days as advised by the medical team,” it said in a statement. It didn't provide further details on his condition.

Mahathir, who was Malaysia's prime minister for two different periods, once was the world's oldest leader. He has had two coronary bypass surgeries but remains robust and sharp witted. He was admitted several times to the same hospital earlier this year.

Mahathir later said he was hospitalized after experiencing shortness of breath due to a shortage of red blood cells. He later had a pacemaker implanted but acquired an infection during the surgery. He has said he thought he was dying at that point but somehow made a recovery.

Read: Mahathir seeks Parliament vote as new Malaysian PM sworn-in

Mahathir ruled Malaysia initially for 22 years until his retirement in 2003. Spurred by anger over government corruption, he led the opposition to a historic election victory in 2018 that ousted the governing party in the first peaceful transfer of power since Malaysia’s independence in 1957.

Mahathir became the world’s oldest leader at 92 for a second stint but that triumph lasted only 22 months as his government collapsed due to defections. Mahathir formed a new ethnic Malay party in 2020 and a Malay alliance this year to contest elections due next year.

Mahathir said in an interview with The Associated Press earlier this month that he plans to contest the polls “If I am strong enough, if I am healthy enough, if they want me to contest, I will contest.”