Mahathir Mohamad, Malaysia’s nonagenarian prime minister, has announced his resignation, threatening the future of the ruling coalition and plunging the south-east Asian country into political turmoil.

He also resigned as chairman of his party, Parti Pribumi Bersatu Malaysia (Bersatu).

According to Malaysian news outlet The Star, the 94-year-old PM Mahathir sent his resignation letter to the king at 1:45 pm “local time”.

After accepting the prime minister’s resignation, Malaysia’s king asked the 94-year-old Mr Mahathir to stay on as interim prime minister until a new leader was appointed.

A tussle has been taking place in Malaysia and the fate of the ruling coalition was in doubt after surprise talks between Mahathir’s party and other groups on forming a new government without Anwar Ibrahim, the man he had earlier named as his successor.

Mahathir, 94, and Anwar, 72, are old rivals and their rivalry has shaped Malaysian politics for decades with tension persisting despite their alliance to win 2018 elections based on a promise that Mahathir would one day cede power to Anwar, according to Al Jazeera.

Anwar accused Mahathir’s party and members of his own party on Sunday of plotting to form a new government with the United Malays National Organisation, the ruling party that was ousted in 2018 on widespread accusations of corruption.

The decision on when Mahathir stepped down will be made after he chairs the Asia-Pacific Economic Cooperation summit in November, the ruling coalition’s presidential council had said Friday night.

This announcement sparked unrest in the coalition, as Anwar had hoped to get a confirmed date on when the promise of him becoming premier would materialize.

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