A lawyer who aided former president Donald Trump’s efforts to undo the 2020 US election results says in a federal court filing that FBI agents seized his mobile phone last week.

John Eastman said the agents took his phone as he left a restaurant last Wednesday night, the same day federal law enforcement officials conducted similar activity around the country as part of broadening investigations into efforts by Trump allies to overturn the election results.

Dr Eastman said the agents who approached him appeared to be serving a warrant from the Justice Department’s Office of Inspector General.

The action was disclosed in a filing in federal court in New Mexico on Monday in which Dr Eastman challenged the legitimacy of the warrant and asked that a court force the FBI to return his phone.

Federal agents last week served a raft of subpoenas related to a scheme by Trump allies to put forward alternate, or fake, slates of electors in hopes of invalidating the election won by Democrat Joe Biden.

Also Wednesday, agents searched the Virginia home of Jeffrey Clark, a Trump Justice Department official who encouraged Mr Trump’s challenges of the election results.

Dr Eastman has been a central figure in the ongoing hearings by the House committee investigating the January 6, 2021, assault on the US Capitol, though he has not been among the witnesses to testify.

– AAP