Jeff Sessions

Sessions acted after it emerged that he had failed at his Senate confirmation hearing to disclose two pre-election meetings with Russia's ambassador to Washington, at a time when Moscow was accused of interfering in the presidential race.

"I have decided to recuse myself from any existing or future investigations of any matters related in any way to the campaigns for President of the United States," Sessions told reporters.

Mr Sessions, a senator at the time, did not disclose the contacts at his January confirmation hearing.

But he stressed on Wednesday he had "never met any Russian officials to discuss issues of the campaign".

Democratic House Minority Leader Nancy Pelosi accused Mr Sessions of "lying under oath" and demanded he resign.

Other Democrats called on him to step aside from an investigation by the FBI - which he oversees as attorney general - into the alleged Russian interference.