Papua New Guinea Prime Minister Peter O’Neill announced his resignation on Sunday after weeks of high-level defections from the ruling party.
O’Neill’s opponents said on Friday they had mustered enough support in parliament to oust him over a range of grievances including a gas deal with France’s Total, which critics have questioned
Political instability is something of a fixture in the resource-rich but poverty-stricken South Pacific nation and O’Neill, who had been leader since 2011, had seen off previous attempts to topple him.
He handed over leadership to Sir Julius Chan, ABC News reported.
Defections from the ruling coalition have been going on for weeks and on Friday, at least nine members switched sides, according to two ministers who were among them.
"It'll only be a formality," defecting Commerce Minister Wera Mori said, referring to what he said would be O'Neill's removal after Parliament reconvenes on Tuesday.
It is not clear whether Mori and his colleagues would seek to move a no-confidence motion, for which there is a complex procedure, or whether by controlling Parliament they can trigger O'Neill's resignation.
O'Neill's office had no immediate comment but has previously expressed confidence he has the necessary numbers to stay leader.
Mori, speaking by telephone from the Laguna Hotel in the capital, Port Moresby, where the opposition has been based for weeks, said that with Friday's defections, O'Neill's opponents could rally 62 members of PNG's 111-seat Parliament to vote him out.
"We've got a lot of issues, that's the reason why we're changing the government," Mori said, when asked the reason for the move against O'Neill.
The opposition has cited unease about the recent natural gas development deal with France's Total and its partners as one of the reasons behind the bid to unseat O'Neill.
Finance Minister James Marape defected in April in the wake of the gas deal, later told PNG's National newspaper he quit because the agreement gave too much ground to the energy firms.
Total did not immediately respond to questions.
Police Minister Jelta Wong said he had also resigned on Friday and the opposition now had enough support to control the floor of Parliament - though that would not be clear until the house reconvenes.
"Nothing is set in stone until the 28th," Wong said.
"We'll see how we go."
It comes after an opposition MP this week sought to have O'Neill disqualified from the leadership on the grounds he may have held Australian citizenship through his father.
But O'Neill's lawyers submitted an affidavit saying he had never been an Australian citizen and did not hold an Australian passport.
The MP, Bryan Kramer, said he would provide proof of the PM's dual citizenship in court or in Parliament next week.
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