Sally Yates had argued that she was not convinced the executive order on immigration is lawful
Donald Trump has fired the acting US Attorney General as the fallout continues from his controversial executive order on immigration.
Sally Yates - who had been serving in the role pending the confirmation of Mr Trump's nominee, Alabama senator Jeff Sessions - had ordered Justice Department lawyers to not defend the executive order.
The order temporarily bans immigration to the US from seven predominantly Muslim countries, and indefinitely halts the country's Syrian refugee programme.
In a letter to lawyers quoted by the New York Times, Ms Yates argued: “At present, I am not convinced that the defense of the executive order is consistent with these responsibilities, nor am I convinced that the executive order is lawful."
The move prompted a furious response from the White House.
In a public statement, the administration said: "The acting Attorney General, Sally Yates, has betrayed the Department of Justice by refusing to enforce a legal order designed to protect the citizens of the United States. This order was approved as to form and legality by the Department of Justice Office of Legal Counsel.
"Ms Yates is an Obama Administration appointee who is weak on borders and very weak on illegal immigration," the statement adds.
The Trump administration has since sworn in Dana Boente - the Attorney for the Eastern District of Virginia - as the acting Attorney General.
In a statement, Mr Boente announced he would rescind Ms Yates' order, saying: "Based upon the Office of Legal Counsel’s analysis, which found the Executive Order both lawful on its face and properly drafted, I hereby rescind former Acting Attorney General Sally Q. Yates January 30, 2017, guidance and direct the men and women of the Department of Justice to do our sworn duty and to defend the lawful orders of our President."
The firing of Ms Yates was heavily criticised by Chuck Schumer, the Democrats' Senate minority leader:
Firing of Sally Yates underscores how impt it is to have an Attorney General who'll stand up to the WhiteHouse when they violate the law.— Chuck Schumer (@SenSchumer) January 31, 2017
The AG should pledge fidelity to the law & the Constitution not the WhiteHouse. The fact that this admin doesnt understand that is chilling.— Chuck Schumer (@SenSchumer) January 31, 2017
Overnight, President Trump also replaced the acting director of the Immigration and Customs Enforcement (ICE) agency.
There was no immediate explanation for the change, NBC reports, with Thomas Homan taking over from Daniel Ragsdale. Mr Ragsdale will return to his previous position as deputy director of the agency.
The executive order on immigration has led to major protests in the US and internationally. It has prompted numerous legal challenges, and is facing political opposition from Democrats and even some prominent Republican lawmakers.
Federal judges in New York and several other states have issued orders temporarily blocking the government from deporting people with valid visas who arrived after the ban started.
Washington state's attorney general has said he is suing Mr Trump over the order and the Council on American-Islamic Relations is doing the same, saying the order appears to favour Christian refugees over Muslim ones and is based on "fear-mongering".
Additional reporting by IRN