Attorney General Jeff Sessions, facing mounting questions over his contact with the Russian ambassador, will not be involved in any investigations into Russian meddling into the presidential campaign and alleged links to the Trump campaign.

Mr Sessions, a key adviser and supporter of Mr Trump's campaign, was accused of lying under oath after it emerged that he twice spoke with Russian ambassador Sergey Kislyak during the 2016 election - conversations he did not disclose to Congress during his confirmation hearing.

Democrats called for his immediate resignation while an increasing number of Republicans also demanded that he withdraw himself from any investigation into contacts between the Trump campaign and the Russian government.

Mr Sessions yielded to growing pressure on Thursday, announcing his decision to recuse himself from any current or upcoming investigation.

He vehemently denied speaking to Mr Kislyak about any matter related to the presidential campaign and insisted that he did not intend to mislead Senators about the conversations.

"I feel like I should not be involved in investigating a campaign I had a role in," he told reporters. "I have recused myself in the matters that deal with the Trump campaign."

His impromptu statement came shortly after President Trump expressed "total" confidence in his attorney general and said he should not step back from any investigation.

The Trump administration is still plagued by persistent questions about its communications with Russia during and after the presidential campaign. The FBI is investigating Russia's interference in the election and any possible connections between the Kremlin and associates of Mr Trump.

US investigators have already stated their belief that the Russian government hacked and leaked emails from Hillary Clinton's campaign as part of sustained efforts to sway the election in Mr Trump's favour.