Australian dual nationals will be able to travel to the United States after being exempted from Donald Trump's immigration ban, which continues to fan a fierce political storm.

Prime Minister Malcolm Turnbull confirmed the development following a call from Australia's ambassador in Washington, Joe Hockey.

The confirmation came hours before Mr Trump took the extraordinary step of firing acting US attorney-general Sally Yates - the government's top legal advisor - for refusing to defend his executive order in court.

The assurance to Australians considering travelling to the US matches those given to the United Kingdom and Canada.

"(Mr Hockey) has had assurances, confirmation, from the White House that Australian passport holders - regardless of their place of birth or whether they are dual nationals or whether they hold another passport - will remain welcome to come and go to the United States in the usual way," Mr Turnbull said on Tuesday.

Mr Turnbull defended his decision not to publicly criticise the Trump ban, which temporarily halts the entire US refugee program and bans all entries from Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen for 90 days.

"When I have frank advice to give to an American president, I give it privately, as good friends should, as wise prime ministers do, when they want to ensure they are best able to protect Australians and Australians' national interest," he said on Tuesday.

"Others can engage in commentary. My job is to stand up for Australia, Australian interests, and deliver, and that's what we've done today."

But Opposition Leader Bill Shorten took a swipe at Mr Turnbull's silence.

While the US should be able to go about its business without interference from Australia, there were some issues where silence would be interpreted as agreement, he said.

"There isn't much point in having the top job if you're not going to back in what you believe," Mr Shorten told reporters in Canberra.

"I don't believe that Australia should sign up to being a satellite and silent on Australian values, full stop."

Mr Turnbull reminded the Labor leader he was not prime minister.

"He will go out on anything that he thinks gives him a political advantage," he said.

"He has no concern about our national interest and our national interest is best protected by me giving private counsel to the United States, our most important ally, (and) publicly refraining from commenting on their domestic policy."

The exemption means Melbourne schoolboy Pouya Ghadirian - a dual Australian-Iranian citizen - should be able to attend a space camp in the US.

Pouya, 15, was refused an entry visa by US consular officials on Monday following Mr Trump's order.

He's now expected to join his classmates on a school trip to visit Orlando, Washington, and the US Space and Rocket Center in Alabama.

Meanwhile, former US ambassador to Australia Jeffrey Bleich condemned the new administration on Facebook, labelling the visa ban illegal and cruel.

"I take no pleasure in condemning our nation's actions," he wrote.

"But the hottest places in hell are reserved for those who, in times of great moral crisis, maintain their neutrality."