US President Donald Trump has hit out at what he says is a "dumb deal" to take "illegal immigrants" from Australia.

The deal to take refugees from Manus Island and Nauru was brokered between the Federal Government and the US in the closing weeks of the Obama administration.

Mr Trump took to Twitter this afternoon to question the deal, which has been the subject of days of mixed messages from the White House.

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The President's tweet — which incorrectly labels refugees "illegal immigrants" and cites "thousands" of people instead of 1,250 — came just hours after details of his conversation with Prime Minister Malcolm Turnbull, which Mr Trump reportedly described as "the worst by far", were published by the Washington Post.

Mr Trump reportedly accused the Prime Minister of seeking to export the "next Boston bombers" to the US, and complained that the deal was going to kill him politically.

Speaking to Sydney radio station 2GB after the President's tweet, Mr Turnbull repeated what the Australian Government had been told through official channels.

"This is not a deal that he would have done or that he would regard as a good deal," he said.

"But the question is will he commit to honour the deal. He has given that commitment."

Mr Turnbull said US officials were already assessing refugees on Nauru and Australian officials were working on the deal in Washington, despite Mr Trump's comments.

He added he was disappointed the details of the call — which he described as "very frank and forthright" — had been leaked.

"The report that the President hung up is not correct," he said.

Mr Turnbull later told Melbourne radio station 3AW that the resettlement deal entered into with the Obama administration "wasn't a commitment to take everybody, sight unseen".

"It was always premised on their very rigorous processing," he said.

When pressed on the President's tweet regarding the deal, Mr Turnbull said "we have a clear commitment".

When asked whether he had a "Plan B" should Mr Trump cancel the deal, the Prime Minister said the Government was exploring "all options" other than resettling refugees in Australia.

He added he had enjoyed his interactions with Mr Trump, saying Australia's alliance with the US remained "rock solid" and was based on generations of commitments, service, courage and partnerships between people.

Sorry, this video has expired Malcolm Turnbull tells 2GB Donald Trump didn't hang up on the call.

Mr Trump's tweet is the latest in a series of mixed messages from the Trump administration over the deal.

Timeline: Conflicting claims 10:00am (AEDT): White House says Donald Trump considering deal

10:00am (AEDT): White House says Donald Trump considering deal 11:00am: State Department says deal is on

11:00am: State Department says deal is on 2:00pm: US Embassy says deal is on

2:00pm: US Embassy says deal is on 3:00pm: Trump tweets he will study deal

Early on Thursday, the White House issued a statement that President Trump had been considering whether to honour the deal.

A short time later, the State Department told the ABC that the deal would go ahead, a statement confirmed by the US Embassy in Canberra.

The State Department said all refugees "would only come to the United States in accordance with the recently signed executive order".

The order — signed last month — banned travel from seven majority Muslim countries for 90 days, suspended all refugee admissions for 120 days and suspended the entry of Syrian refugees indefinitely.

Labor's acting foreign affairs spokesman Richard Marles highlighted the Opposition's support for the deal, but called on the Prime Minister for further information to be made public.

"Australians deserve to know what he's going to do," he said.

"And if the Prime Minister doesn't know whether he has a deal, he needs to tell us what his plan is now that he has failed to stand up for Australia's interests and values."

Professor of international law at the Australian National University, Donald Rothwell, said Mr Trump was free to tear up the deal if he saw fit.

"The Australia-US refugee deal has not taken the form of a treaty, so there is no legally binding instrument — and as such no legal obligation — upon the Trump administration to honour the deal," he said.