Australia's immigration chief has conducted a secret visit to the United States to reach out to Donald Trump officials and spruik a refugee deal Malcolm Turnbull struck with outgoing President Barack Obama.

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.