Steve Bannon File photo: Xinhua

Outgoing US President Donald Trump on Wednesday signed the documents to pardon former White House aide Steve Bannon on his final full day at the White House.

Bannon, 67, helped Trump on the campaign trail during the 2016 presidential elections and was a senior White House adviser. But in August 2017 he was charged with defrauding donors of more than a million dollars as part of a fundraising campaign purportedly aimed at supporting Trump's border wall.