Attorney General William Barr (Photo: Reuters)

"There's been one assertion that would be systemic fraud and that would be the claim that machines were programmed essentially to skew the election results," Mr Barr said, affirming that the Department of Justice and the Department of Homeland Security have investigated that claim, and so far they haven't seen anything to substantiate it.

Reacting to Barr's comments, Trump campaign lawyers Rudy Giuliani and Jenna Ellis said in a joint statement: "With the greatest respect to the Attorney General, his opinion appears to be without any knowledge or investigation of the substantial irregularities and evidence of systemic fraud."