Malaysian Prime Minister Mahathir Mohamad on Monday announced his resignation from the post, paving the way for a possible formation of a new government.
The 94-year-old leader sent a two-line resignation letter to the king, Al Jazeera reported.
Mahathir's party, Parti Pribumi Bersatu Malaysia, has also quit the ruling government coalition, Pakatan Harapan (Alliance of Hope), according to party president, Muhyiddin Yassin, in a social media post.
Mahathir's decision follows a weekend of political wrangling, after it was reported on Sunday night that his party was planning to form a new government that would exclude his successor, Anwar Ibrahim.
The tussle between old rivals Mahathir and Anwar, 72, is the latest chapter in the long-running political saga between two of the country's most prominent political figures.
Anwar and Mahathir had united ahead of the 2018 election to drive out the UMNO-dominated Barisan Nasional coalition that had ruled the South-East Asian country for six decades. The Pakatan Harapan coalition emerged as the surprise winner in the polls that led to the ouster of then-Prime Minister Najib Razak.
But tensions in the Pakatan Harapan coalition had been growing, as Mahathir resisted setting a specific timetable for keeping his promise to hand power to Anwar.
Anwar was Mahathir's deputy when the latter was the prime minister during his first stint from 1981 to 2003. But Mahathir sacked him in 1998 after they disagreed on policies to handle the financial crisis in the country.
Soon afterwards, Anwar was jailed for sodomy, charges he said were trumped up.
( With inputs from ANI )