A total of 12 MPs in the Papua New Guinea Government of Jame Marape have now switched sides, joining the opposition, ahead of an expected vote of no confidence in the prime minister.
Governments in PNG have 18 months grace after an election when opponents cannot bring motions for votes of no confidence.
That period, in place since August 2022, expires this weekend.
RNZ Pacific correspondent in PNG, Scott Waide, said the latest resignations came on Thursday with the East Sepik Governor Allan Bird and Sam Basil Jr, who holds the Bulolo Open seat, strongly criticising Prime Minister Marape.
"Both expressed that they were disappointed in the performance of the Prime Minister and they decided to move. Sam Basil Jr in particular expressing that he was disappointing in the manner in which resources were being distributed for MPs on both sides of the House," he said.
Waide said Bird raised concerns about Marape's alleged involved in the Paul Paraka payments - something the prime minister has strenuously denied.
There are now 23 MPs on the opposition benches but a successful vote would require the backing of 60 members.
No motion has yet been filed, though the possibility of a motion is being widely discussed in PNG.
Meanwhile, Marape became the first Pacific Island leader to address the Australian federal parliament on Thursday, where he stressed about PNG's desire to become an economically independent nation.