Former prime minister Malcolm Turnbull has unleashed on Kevin Rudd and Tony Abbott, describing them as "miserable, miserable ghosts" who should have left Parliament the moment they lost the top job.

Key points: Mr Turnbull issued the comments at a forum in New York

Mr Turnbull issued the comments at a forum in New York He also said he wished Prime Minister Scott Morrison well

He also said he wished Prime Minister Scott Morrison well Mr Turnbull said Mr Abbott and Mr Rudd should "move on"

Speaking at a forum in New York, Mr Turnbull also described the recent Liberal leadership change as "crazy" and revealed "private polling" showed the Coalition was tracking ahead of Labor in marginal seats.

"We were very, very competitive," he said in the audio obtained by Channel Nine.

"But for reasons that they've not been able to explain, you know, there was an element of the party and of the media that wanted to blow the government up, and they did.

"And of course, they didn't get their guy up, they got ScoMo (Scott Morrison) — and I wish him well."

Malcolm Turnbull says Kevin Rudd and Tony Abbott should have moved on after losing their leadership spills. ( AAP: Alan Porritt )

The former prime minister is clearly still angry at Home Affairs Minister Peter Dutton and his forces for launching the leadership challenge six weeks ago.

But Mr Turnbull justified his decision to quit Parliament immediately, saying "when you stop being prime minister, that's it'".

"There is no way I would be hanging around like Kevin Rudd or Tony Abbott," he said.

"Seriously, these people are like, sort of miserable, miserable ghosts.

"Move on."

'Come over for a cuppa': Rudd

Mr Rudd responded to the comments on Twitter on Monday, saying Mr Turnbull has been frequently appearing in the press himself since leaving office.

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"In case you didn't notice, I left parliament for NYC five years ago. Why not come over for a cuppa?" he wrote.

Mr Turnbull's comments come a day after Mr Morrison told the ABC's Insiders program that he was confident the Coalition would have won the next election under Mr Turnbull.

Both Mr Rudd and Mr Abbott created deep internal divisions after losing their prime ministerships in 2009 and 2015 respectively.

As a backbencher in the Gillard government, Mr Rudd was the source of a series of damaging leaks that cruelled Julia Gillard's hopes of returning a majority government at the following election.

Mr Abbott famously declared there would be "no wrecking, no undermining, no sniping" after he was deposed as leader but spent the next three years publicly intervening in policy debates and became a key figure in Mr Turnbull's ousting.

Speaking in New York, Mr Turnbull said he would continue to express his views on big issues like "energy and constitutional matters" but declared his days as a partisan politician are over.

"I'm not going to become a Trappist monk — but my days of being involved in partisan politics are over," he said.

Mr Turnbull and his wife Lucy escaped to New York almost immediately after he lost the top job.

From there, he has maintained a relatively high profile, reflecting on his leadership with veteran Reuters editor Sir Harold Evans, supporting an anti-tobacco initiative at the United Nations and now giving a speech at a young leaders' forum.

At the Reuters event, Mr Turnbull again took aim at "his opponent" Mr Abbott, describing him as a "right-wing character"

The Turnbulls are not expected to return home until after the Wentworth by-election later this month.