President Donald Trump has ordered his administration to investigate former President Joe Biden’s use of an autopen to sign pardons and other documents.

The House Judiciary Committee is expected to interview former Hunter Biden special counsel David Weiss behind closed doors on Friday, two sources familiar with the interview told CNN, as part of a broader Republican effort to revisit previous probes into the Biden family that stalled last Congress but are gaining new momentum now that Republicans control both chambers of Congress and the White House.

Donald Trump accuses the former president's aides of covering up his "mental state" - a claim Biden says is "ridiculous".