Washington: Canberra's get-out-of-jail card on the future of the hundreds of Australia-bound refugees on Nauru and Manus Island may have a very short shelf-life, with the head of a prominent US anti-immigration think tank warning: "This is the kind of thing the Trump administration will nix on Day 1."

At the weekend, Prime Minister Malcolm Turnbull revealed a "one-off" deal with Washington, under which, for 1800 detainees in the Australian operated detention facilities, resettlement in the US would be an alternative to returning to their home countries or remaining in Nauru indefinitely.

Washington has not confirmed the deal publicly. But, after a brutal US election campaign, in which "illegal" immigration was the most bitterly contested policy, Mark Krikorian, executive director of the influential Centre for Immigration Studies, predicted a "firestorm" of opposition from anti-immigration activists.

"It's so difficult to justify," he told Fairfax Media. "I don't expect any Republicans will defend it. I can't see a lot of Democrats defending it either. My sense is that when the word gets out on this, it'll be dead on arrival."