The FBI seized the phone of former U.S. President Donald Trump's election attorney, John Eastman, last week, the lawyer said in a court filing on Monday.

Eastman is considered one of the key figures in the Trump campaign's attempt to reverse the outcome of the 2020 U.S. election. He has been under intense scrutiny in relation to the probes into the Jan. 6, 2021 attack on the U.S. Capitol by Trump supporters.