The U.S. special counsel leading a criminal probe into Joe Biden's son said a former FBI informant was charged with lying about the president and Hunter Biden's involvement in business dealings with Ukrainian energy company Burisma Holdings.

In a statement on Thursday, Special Counsel David Weiss said a federal grand jury had indicted Alexander Smirnov, 43, on charges of making a "false statement" and "creating a false and fictitious record" in relation to an FBI probe. Smirnov faced a maximum penalty of 25 years in prison if convicted.