Department of Immigration and Border Protection secretary Michael Pezzullo and other senior bureaucrats have in recent weeks engaged in a series of high-level meetings with figures connected to President-elect Trump, and with officials from the Department of Homeland Security, to discuss operational details of the deal.

Fairfax Media has learned that Mr Pezzullo was in the United States to offer detailed briefings on President Obama's offer to take an undisclosed number of refugees from Manus Island and Nauru, and provide broader context about Operation Sovereign Borders, the tough border protection policy introduced under Tony Abbott.

The meetings have been designed to assuage Republican concerns about the deal and ensure it holds after President-elect Trump is inaugurated in late January. There were fears in Australia that Mr Trump - who made a hardline approach to immigration one of the hallmarks of his election campaign - could tear up the agreement, which the Turnbull government had spent the better part of this year securing.

As one Turnbull government source put it to Fairfax Media: "If you were a Republican you might think 'what the hell is this?'."

"But if you get a briefing from us on the context . . . it calibrates it from a Republican perspective."

The meetings were scheduled amid demands from senior US Republicans for the White House to make public information about the refugee resettlement deal.

The chairmen of the powerful House and Senate Judiciary Committees in Washington, congressman Bob Goodlatte and senator Chuck Grassley, have objected to "secret" negotiations with Australia, which they have said has "left Americans in the dark".

Under the proposed deal, as many as 1800 asylum seekers held on Nauru and Manus Island could be resettled in the United States.

Last week, a confident Prime Minister Malcolm Turnbull told Fairfax Media the deal had been "secured".

When asked whether the refugee deal could be scuppered by the incoming Trump administration, Mr Turnbull has repeatedly said his government would deal with one administration at a time.

But privately, sources believed there was some chance the deal could be scuppered and the senior officials were dispatched to head-off what would be a disastrous political setback for the Turnbull government.

The United States has an annual intake of about 100,000 refugees. The Manus Island and Nauru refugees would be within the existing intake. Australia has in turn promised to take refugees from the violence-plagued "northern triangle" countries of Guatemala, Honduras and El Salvador currently living in camps in Costa Rica.

Immigration Minister Peter Dutton announced on Monday that Australia had signed a new memorandum of understanding that will see Vietnamese nationals intercepted at sea with no legal right to enter or remain in Australia returned to their home country.

Since 2015, 113 Vietnamese nationals on three vessels have been sent back to Vietnam after being intercepted by the Australian Border Force.

Under the Turnbull government's bid to shut down the offshore detention system, refugees or asylum seekers on Manus Island and Nauru who are not allowed or don't want to resettle in America would be sent home or given a visa to stay on Nauru.

A spokesperson for the Department of Immigration and Border Protection said Australian officials "including at the rank of secretary" routinely travel to the United States for "discussions on matters of mutual interest."

Comment was sought from Immigration Minister Peter Dutton.

Follow James Massola on Facebook