United States President Donald Trump has sacked acting Attorney-General Sally Yates, accusing her of "betraying the Department of Justice" after she directed her attorneys not to defend his controversial executive refugee and immigration ban.

"I am responsible for ensuring that the positions we take in court remain consistent with this institution's solemn obligation to always seek justice and stand for what is right," Ms Yates said.

"At present, I am not convinced that the defence of the executive order is consistent with these responsibilities, nor am I convinced that the executive order is lawful."

A statement from the White House confirmed Mr Trump had "relieved Ms Yates of her duties", accusing her of "betraying the Department of Justice".

"The Acting Attorney-General, Sally Yates has betrayed the Department of Justice by refusing to enforce a legal order to protect citizens of the United States," the statement read.
"It is time to get serious about protecting our country.

"Calling for tougher vetting for individuals travelling from seven dangerous places is not extreme."

The Democratic appointee's directive was only ever likely to be temporary, given that Senator Jeff Sessions, Mr Trump's pick for attorney-general, will likely move to uphold the president's policy.

US attorney for the Eastern District of Virginia Dana Boente was sworn in as acting Attorney-General about 9:00pm Monday (local time) to replace Ms Yates in the meantime.

Still, Ms Yates's abrupt decision deepened the chaos surrounding Mr Trump's order.

At least three top national security officials — Defence Secretary James Mattis, Homeland Security Secretary John Kelly and Rex Tillerson, who is awaiting confirmation to lead the State Department — have told associates they were not aware of details of the directive until around the time Mr Trump signed it.

Leading intelligence officials were also left largely in the dark, according to US officials.

Tennessee senator Bob Corker, the top Republican on the Senate Foreign Relations committee, said that despite White House assurances that congressional leaders were consulted, he learned about the order in the media.

The fallout was immediate, with friction growing between Mr Trump and his top advisers and a rush by the Pentagon to seek exemptions to the policy.

The White House approach also sparked an unusually public clash between a president and the civil servants tasked with carrying out his policy.

White House divide deepens as Trump doubles down

A large group of American diplomats circulated a memo voicing their opposition to the order, which temporarily halted the entire US refugee program and banned all entries from seven Muslim-majority nations for 90 days.

"They should either get with the program or they can go," Mr Spicer said.

The blowback underscored Mr Trump's tenuous relationship with his own national security advisers, many of whom he met for the first time during the transition, as well as with the Government bureaucracy he now leads.

While Mr Trump outlined his plan for temporarily halting entry to the US from countries with terror ties during the campaign, the confusing way in which it finally was crafted stunned some who have joined his team.

Mr Mattis, who stood next to Mr Trump during the signing ceremony, is said to be particularly incensed.

A senior US official said Mr Mattis, along with Joint Chiefs chairman Joseph Dunford, was aware of the general concept of Mr Trump's order, but not the details.

US officials and others with knowledge of the Cabinet's thinking insisted on anonymity in order to disclose the officials' private views.