Donald Trump is not ruling out both pardoning Michael Flynn and bringing the retired Army general, whom he fired just 25 days into his term, back into his administration.

The president, who has in the past has broken with previous presidents by weighing in on Justice Department cases, said he thinks evidence of internal FBI communications released earlier Thursday show a federal judge should completely "exonerate" Mr Flynn.

"I would certainly consider it," Mr Trump said of re-hiring Mr Flynn, who faces federal charges on lying to investigators about his conversations with a Russian official and about his private-sector lobbying work. "I think he's a fine man."

Documents turned over to the Justice Department show FBI investigators debating whether and how to inform Mr Flynn before a January 2017 interview that he could face federal charges. Their contents have led Mr Trump and many Republicans to call for all charges against the retired general to be dropped.

"What is our goal? Truth/admission or to get him to lie, so we can prosecute him or get him fired?" an unidentified person wrote in notes apparently taken before Flynn was interviewed on Jan. 24, 2017, four days after Trump took office.

Mr Trump denied Mr Flynn had done anything wrong when he fired him in February 2017, saying instead he let Mr Flynn go because he misled Vice President Mike Pence.

Sources said at that time that Mr Pence was livid that Mr Flynn lied to him, and convinced the president to fire the man who then was his national security adviser.