White House spokesman Sean Spicer said the president had named Dana Boente, US Attorney for the Eastern District of Virginia, as her replacement.

Mr Trump had earlier tweeted: "The Democrats are delaying my cabinet picks for purely political reasons. They have nothing going but to obstruct. Now have an Obama AG."

Ms Yates, a Democrat, was appointed only on January 20, until the successor for Loretta Lynch was confirmed by the Senate.

Mr Trump's choice, Senator Jeff Sessions, is awaiting Senate confirmation.

Ms Yates angered the Trump administration when she directed Justice Department lawyers not to defend Mr Trump's executive refugee and immigration ban, saying she was not convinced that the order was lawful.

Mr Trump said Ms Yates "has betrayed the Department of Justice by refusing to enforce a legal order designed to protect the citizens of the United States".

He said: "Ms Yates is an Obama Administration appointee who is weak on borders and very weak on illegal immigration.

"It is time to get serious about protecting our country. Calling for tougher vetting for individuals travelling from seven dangerous places is not extreme. It is reasonable and necessary to protect our country."

The president said Mr Boente would serve as acting Attorney General until Mr Sessions "is finally confirmed by the Senate, where he is being wrongly held up by Democrat senators for strictly political reasons".

Mr Boente said: "I am honoured to serve President Trump in this role until Senator Sessions is confirmed. I will defend and enforce the laws of our country to ensure that our people and our nation are protected."

Mr Boente was sworn in privately late on Monday, the White House said.

The refusal by Ms Yates to defend the executive order was largely symbolic given that Mr Sessions will almost certainly defend the policy once he is sworn in.

Mr Sessions is expected to be confirmed today by the Senate Judiciary Committee and could be approved within days by the full Senate.

Mr Boente immediately ordered Justice Department lawyers to "do our sworn duty and to defend the lawful orders of our President".

The clash between the new president and the nation's most senior law enforcement officer had laid bare the growing dissent over Mr Trump's refugee and immigration ban.

His executive order temporarily halted the entire US refugee programme and banned all entries from seven Muslim-majority nations for 90 days.

Ms Yates had said: "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.

"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."