The fate of Malaysia's ruling coalition is in doubt after surprise talks between Prime Minister Mahathir Mohamad's PPBM party and other groups on forming a new government that would exclude his anointed successor and coalition partner, Anwar Ibrahim.

The tussle between old rivals Mahathir, 94, and Anwar, 72, has shaped Malaysian politics for decades, with tensions persisting despite their 2018 alliance to win the elections based on a promise that Mahathir would one day cede power to Anwar.

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On Sunday, Anwar accused Mahathir's party and "traitors" in his own People's Justice Party (PKR) of plotting to form a new government with the United Malays National Organisation (UMNO) - part of the Barisan Nasional coalition, which ruled for over 60 years and was removed in a 2018 elections upset amid accusations of corruption.

He also said a meeting convened on Monday by a group of politicians was a political "betrayal".

Sources told Reuters that Mahathir's PPBM (the Malaysian United Indigenous Party) and a faction within Anwar's PKR met officials from UMNO and the Islamist PAS party on Sunday in efforts to form a new coalition.

Asked about what transpired during the Sunday meeting, which triggered talks about a new government, Foreign Minister Saifuddin Abdullah, who attended, told Al Jazeera that he was not at liberty to discuss it.

Saifuddin, who is a member of Anwar's PKR, also would not comment about his future as the country's top diplomat.

Malaysian stocks fell more than 2 percent when markets opened on Monday, affected by the political uncertainty.

Mahathir's party, UMNO and PAS met with the king on Sunday, media said, though it was not clear what they discussed and whether the new proposed coalition would secure backing from the king, whose role is largely ceremonial.

#Malaysia's Economic Affairs Min Azmin Ali emerges from meeting of different parties that could decide realignment of the govt of PM #Mahathir as early as Monday. Azmin is Anwar's rival from within the People's Justice Party, which is part of Pakatan Harapan governing coalition. pic.twitter.com/dQDoYWhlS5 — Ted Regencia تِد (@tedregencia) February 23, 2020

Anwar to meet king

The king can dissolve Parliament on the advice of the prime minister and his assent is required for the appointment of a prime minister or senior officials.

But it is unclear what his role would be if the ruling coalition changed without a change in prime minister.

Anwar was also due to meet the king at 2:30pm (06:30 GMT) on Monday, his spokesman said, but gave no details of what he would seek.

Earlier in the day, Anwar also held meetings with other politicians from the current coalition government.

Devamany Krishnasamy, deputy president of the Malaysian Indian Congress, who was also present in Sunday's meeting, told Al Jazeera that Mahathir had the numbers to form a new government.

"This is politics. It happens around the world. The constitution says the Parliament can decide that any majority can run the government, and you must get the consent of the agong (king), as simple as that," said Devamany, whose party is a founding is aligned with the current opposition party.

Anwar and Mahathir united ahead of the 2018 election to drive out the UMNO-dominated Barisan Nasional coalition.

But tensions had been growing between the two in their Alliance of Hope (Pakatan Harapan, or PH) coalition, as Mahathir resisted setting a specific timetable for keeping his promise to hand power to Anwar.

PH's political fortunes have also been waning, with defeat in five recent by-elections.

Anwar also had a split with party mate, Mohamed Azmin Ali, the economic affairs minister, who was among those who joined the meeting on Sunday night.

Anwar was Mahathir's deputy when the latter served as prime minister from 1981 to 2003 but Mahathir sacked him in 1998 after they disagreed on how to handle the financial crisis Malaysia was going through at the time.

Soon afterwards, Anwar was jailed for sodomy, charges he says were trumped up.

With additional reporting by Ted Regencia in Kuala Lumpur