The Immigration Department and the Department of Foreign Affairs and Trade (DFAT) appear to be at odds over the refugee resettlement deal with the United States.

Last week, DFAT told a Senate committee that the US could resettle no-one from Australia's offshore immigration centres and still argue it has honoured its deal with the Turnbull Government.

Andrew Goledzinowski, DFAT's Ambassador for People Smuggling and Human Trafficking, said the agreement did not require the US to take in any particular number of refugees.

When asked by Greens senator Nick McKim whether the US could resettle no-one and still claim it had complied with the agreement, Mr Goledzinowski responded "technically, I think that's the case".

But Immigration Department Secretary Michael Pezzullo has disputed this, telling a Senate committee hearing last night that "I don't agree it could be zero".

"The arrangement struck with the Obama administration included an aim or a goal of 1,250 persons," he said.

"So honouring the agreement would take you into that ballpark."

Resettlement process underway

Officials from the US Department of Homeland Security are set to begin fingerprinting refugees in preparation for resettlement.

The deal for the US to resettle refugees from Manus Island and Nauru was brokered in the closing weeks of the Obama administration.

A figure of 1,250 was reportedly included in the wording of the agreement, but officials are yet to confirm any resettlement numbers.

The ABC understands that of roughly 900 refugees who may be under consideration on Nauru, about 600 had first interviews conducted by officials from the US resettlement team based in Bangkok in December and January.

Of about 600 who may be eligible on Manus Island, around half had first interviews during the same period.

Deputy Immigration Secretary Rachel Noble told the hearing on Monday that the officials will remain on Nauru until March 30, carrying out fingerprinting, before moving to Manus Island on April 4.

Ms Noble said a separate group of officials from Homeland Security would conduct security interviews on Nauru from March 30 to April 20, before doing the same on Manus Island from May 2 to May 12.