'I will treat all former Prime Ministers with respect': Morrison sidesteps Turnbull claims of a history of lying

Prime Minister Scott Morrison has said he will "treat all former Prime Ministers with respect" following an extraordinary broadside from predecessor Malcolm Turnbull in which he was called a liar.

The PM is currently in Dubai en-route to Australia after attending the COP26 summit in Glasgow where the French delegation claimed Mr Morrison lied to them about Australia's plans to scrap a $90 billion submarine deal.

When asked about Mr Turnbull's comment, Mr Morrison refused to be drawn into a tit-for-tat commentary.

"Australia made the decision not to go ahead with the contract for submarine that was not going to do the job that Australia needed to do, and I'll never make any apologies for that decision," Mr Morrison said.

"As you know, I always treat all former Prime Ministers with respect, and I'm going to continue to do that."

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The retort comes after Mr Turnbull said the Prime Minister had a personal history of lying.

"Oh, he's lied to me on many occasions," Mr Turnbull said when asked about the spat between Mr Morrison and French President Emmanuel Macron.

"I mean there's quite a few examples in my book, but he's — Scott has always had a reputation for telling lies."

Mr Turnbull, who was replaced by Mr Morrison as leader of the Liberal party and Prime Minister in 2018 after an acrimonious leadership battle, said disingenuous behaviour would always reflect badly on a leader.

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"But when you do that, as the leader of the nation, internationally, it reflects on us all," he said.

"Now look, deceiving people is bad wherever you do it, but when you do it at an international level, it has much graver ramifications."

Mr Morrison was due to speak this morning after Australia signed up to a 100-nation agreement to end deforestation by 2030, but instead changed plans and opted to start the journey home.

The spat over the cancellation of a $90 billion deal to buy diesel submarines from France's Naval Group in favour of nuclear-powered vessels made available through a new alliance with the US and the UK has boiled continuously on the sidelines of world leader meetings in Europe this week.

Asked by journalists on Monday whether he thought Mr Morrison lied to him about the deal, Mr Macron said: "I don't think, I know".

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Mr Morrison denied having lied and labelled the French President's criticism "slurs" and "sledging", in a detailed rebuttal on Tuesday accompanied by a message leaked to media purporting to show Mr Macron knew the deal was at risk before he was told.

"Should I expect good or bad news for our joint submarines ambitions?" Mr Macron reportedly asked, two days before the AUKUS coalition was set to be announced as Mr Morrison was trying to set up a call.

US President Joe Biden has admitted the handling of the landmark agreement that will allow Australia to buy nuclear-powered submarines using US and UK technology was "clumsy".

But Mr Morrison has insisted the dumping was essential for Australia's national security and bound to upset the French no matter how it was handled.

Mr Morrison insisted he made Mr Macron aware aware Australia was considering alternatives to the French deal when they had dinner in the Élysée Palace after the G7 meeting in June.

He said a "full-court press" from the French defence system in the immediate aftermath was proof of that but a joint French-Australian statement in late August — a little more than two weeks before the AUKUS announcement — "underlined the importance of the Future Submarine program".

Mr Morrison said approaching the US about using their nuclear-powered submarines was "always an option" but defended the initial French deal.