The White House has backtracked on a promise to honour a refugee deal with Australia, saying President Donald Trump is still considering whether it will go ahead.

Key points: Refugee deal concerns 1,250 refugees, some from countries on Trump's travel ban list

Refugee deal concerns 1,250 refugees, some from countries on Trump's travel ban list Deal struck between Obama administration and Turnbull Government

Deal struck between Obama administration and Turnbull Government President still deciding whether to honour the deal after executive order suspends US refugee program

The clarification came soon after White House press secretary Sean Spicer said the deal was going ahead provided the refugees were subjected to "extreme vetting" procedures.

In a follow-up phone call to the ABC, a White House source said if the President did decide to honour the deal, it would only be because of America's "longstanding relationship with Australia".

The ABC has spoken to Australian officials who say the resettlement refugee deal was confirmed in the conversation between the President and Prime Minister Malcolm Turnbull.

The officials said Mr Trump had instructed Homeland Security officials to "get on with it", and said that was reinforced today by Homeland Security officials in meetings with Australian officials in Washington.

When pressed on the deal today, Prime Minister Malcolm Turnbull said the Trump administration remained committed to the deal.

"That was the assurance the President gave me when we spoke on the weekend," he said.

Mr Turnbull defended the vetting process underway offshore, saying he expected that it would be "very, very rigorous".

"We don't cut corners or compromise on keeping Australians safe, and the United States Government has exactly the same attitude," he said.

"So, vetting will always be rigorous and that has always been part of the agreement. Naturally, it's the United States Government [that] determines who goes into the United States. The Australian Government determines who comes into Australia. And they will do their own extremely rigorous vetting of people that are the subject, or potentially the subject, of the agreement."

Deal covers more than 1,000 people

Earlier Mr Spicer had said the deal, struck between the Obama administration and Turnbull Government, would include approximately 1,250 refugees, many from countries covered by the new administration's bans on entry to residents from seven majority Muslim nations.

"There will be extreme vetting applied to all of them," he said.

"That is part and parcel of the deal that was made, and it was made by the Obama administration with the full backing of the United States Government."

According to the latest statistics from the Immigration Department, there are 871 people on Manus Island and 383 people on Nauru.

The ABC understands most of the refugees are from Iran, with some also from Iraq and Somalia, three of the countries on the Trump administration's travel ban list.

At a briefing earlier, US Homeland Security Secretary John Kelly said "we are looking at various options right now" with regard to "extreme vetting".

"There are many countries — seven that we are dealing with right now — that in our view don't have the kind of law enforcement, records keeping that can convince us that one of their citizens is indeed who that citizen says they are and what their background might be," he said.

"So we are developing what additional vetting, extreme vetting might look like, and we will certainly work with countries on this."

Deal had been called into question by executive order

The deal had come into question after Mr Trump signed an executive order suspending his country's refugee program.

On Saturday the President put a four-month hold on allowing refugees into the US and temporarily barred travellers with passports from seven Muslim-dominated countries.

Mr Turnbull spoke with Mr Trump by phone on Sunday, during which time it is understood the President agreed to honour the deal.

Before the call, Mr Turnbull said there was a section in Mr Trump's executive order which stated officials could still admit refugees under pre-existing international agreements.

The ABC understands that section was included in the final version of the executive order after the Prime Minister's office intervened.

"We are very confident and satisfied that existing arrangements will continue," Mr Turnbull said before the call.

"It's quite clear that the administration has set out in the order the ability to deal with existing arrangements."

Deputy Prime Minister Barnaby Joyce would not be drawn on the fate of the refugees who did not meet the processing demands of the US.

"If they don't fulfil the US's vetting, then they're not getting into the US," he told the ABC.

"How they deal with issues with Australia is something entirely different."

Last week senior Australian Government sources said they were confident the orders would not impact the deal to resettle refugees currently on Manus Island and Nauru, entered into late last year with former president Barack Obama.

Authorities had hoped to begin moving people to the US at the start of this year.