Former US attorney general William Barr said President Donald Trump's conduct as a violent mob of his supporters stormed the US Capitol was a 'betrayal of his office and supporters'.

Iran Press/America: Barr, who stepped down just before Christmas after his previously warm relationship with Trump broke down, said that 'orchestrating a mob to pressure Congress is inexcusable'.

His comments come a day after rioters broke into the US Capitol, forcing Congress members to halt the ongoing vote to certify president-elect Joe Biden's election. 

Barr resigned last month amid lingering tension over the president's baseless claims of election fraud and the investigation into Biden's son Hunter. 

Barr, 70, was one of Trump's most loyal and ardent defenders in the Cabinet.