Former U.S. President Donald Trump's team may not have returned all the classified records removed from the White House at the end of his presidency even after an FBI search of his home, U.S. prosecutors warned on Thursday, calling it a potential national security risk that needs investigation.

That revelation came in a Justice Department court filing asking U.S. District Judge Aileen Cannon to let it continue reviewing about 100 classified records seized by the FBI at Trump's Mar-a-Lago estate while it investigates whether classified documents were illegally removed from the White House and improperly stored there.

Trump is under investigation for retaining government records, some of which were marked as highly classified, at the resort in Palm Beach, Florida, his home after leaving office in January 2021.