Malaysia’s Mahathir Mohamad unexpectedly resigned as Prime Minister on Monday, leaving the Southeast Asian nation in political turmoil, but the country’s monarch asked him to stay on as interim Premier until a successor is appointed.

The resignation of Mahathir, 94, broke apart a coalition with old rival Anwar Ibrahim, 72, that had scored a surprise election victory in 2018 and was not part of a pre-election promise that Mahathir would one day cede power to Anwar.

But it immediately drew calls from some quarters for the world’s oldest government leader to return.

The decision, which Mahathir did not explain, followed surprise talks at the weekend between members of his coalition and the Opposition on forming a new government.

The king accepted Mahathir’s resignation after meeting Mahathir, chief secretary Mohd Zuki Ali said.

“However, His Highness has given his assent to appoint Mahathir Mohamad as interim prime minister, while waiting for the appointment of the new Prime Minister. Hence until then, (Mahathir) will manage the country’s affairs until a new Prime Minister and cabinet are appointed,” Mohd Zuki said.

Anwar and people close to Mahathir said he had quit after accusations that he would form some sort of partnership with Opposition parties he defeated less than two years ago on an anti-corruption platform.