Prime Minister Scott Morrison has cancelled plans to visit Papua New Guinea next week, as political chaos engulfs Port Moresby.

Mr Morrison has agreed to defer his visit to the Pacific nation, where Prime Minister James Marape is under pressure to resign.

Mr Marape came to power in May last year but there has been growing unrest in his coalition.

Several Government MPs, including Deputy Prime Minister Sam Basil, on Friday crossed the floor to join the Opposition, which voted to suspend Parliament.

Foreign Affairs Minister Patrick Pruaitch and Attorney-General David Steven also abandoned the Government.

Mr Marape insists he can still summon the numbers to hold on to power but big question marks hover over his political future.

Mr Morrison on Friday said he still intended to travel to Papua New Guinea, despite the political uncertainty and Mr Marape said "there was nothing stopping him from coming" but "it was up to him".

A spokesperson for Mr Morrison said Mr Marape had since contacted him and asked him to defer his visit.

PNG Opposition warns against visiting PM while he's 'trying to cling on to power'

If the Australian leader had pressed ahead with the visit, he risked being embroiled in a political storm.

Opposition Leader Belden Namah criticised Mr Morrison's planned trip before launching his parliamentary challenge to Mr Marape.

Mr Namah said the timing of the visit was "highly suspicious" and suggested Mr Morrison was visiting to prop up Mr Marape.

"It is bad diplomacy and is tantamount to an attempt to influence PNG's political process," he said in a statement.

Mr Namah told the ABC he was pleased with Mr Morrison's decision not to visit Port Moresby.

"I want to thank the Australian PM for making a very responsible decision. It is the right thing to do," he said.

Mr Namah said the "incoming government looks forward to welcoming" Mr Morrison to PNG "after the swearing-in of the prime minister and cabinet".

"It would have been an embarrassment for Prime Minister Morrison if he has proceeded with the visit and had to meet with James Marape during his last days of desperately trying to cling on to power," he said.

Mr Marape said the "recklessness" of Mr Namah was to blame for the cancellation of the "important face-to-face meeting".

"The visit has been hijacked by Belden Namah through his selfish no-confidence move against me," he said.

"People of PNG must know that Namah is a 'leader' who claims to represent their interests, however, causes instability by stopping Australia — our biggest bilateral partner — from coming in.

"That's recklessness of the highest order."

There could be weeks of political uncertainty ahead in PNG.

The Opposition voted to suspended Parliament until the start of December, when a vote to change prime ministers would be possible.

In the lead-up to the return of Parliament, both sides will go into what are called "camps", where they stay together to ensure their numbers and attempt to strengthen their positions by luring MPs from the opposing side.

The Opposition team, which had gathered in a hotel in Port Moresby, has now flown out of the city.

They are expected to spend the next two weeks in Vanimo, which is in Mr Namah's electorate.

Mr Marape said he was "confident" of regaining numbers and his Police Minister Bryan Kramer posted on Facebook that the National Executive Council would meet next week to decommission 13 ministers, presumably those who were part of the walkout.

Mr Morrison was due to visit Papua New Guinea on the way home from a trip to Japan.

He will become the first foreign leader to meet the new Japanese prime minister Yoshihide Suga in Tokyo when he flies to the capital next week.

The Prime Minister will then quarantine for 14 days when he returns to Australia, planning to join Question Time in Parliament via video link from The Lodge.