US Attorney General Jeff Sessions has acknowledged that he was aware of contact between Donald Trump's election campaign and Russian intermediaries, again modifying a previous statement about the extent of connections to Moscow.

The comment by Mr Sessions to a House of Representatives panel did not reveal any new link between the Trump team and Russia.

However, it was another example of the top US law enforcement official offering a different version of events as politicians try to work out if the Trump campaign colluded with Russia in the 2016 election.

Mr Sessions told the House Judiciary Committee that he now recalls a meeting last year with then-candidate Trump where a campaign adviser said he had connections with Moscow and could help arrange a Trump meeting with Russian President Vladimir Putin.

"I do now recall" the meeting where adviser George Papadopoulos made the proposal, Mr Sessions said, "but I have no clear recollection of the details of what he said during the meeting."

Mr Sessions has previously told Congress he was unaware of any Trump campaign contacts with Russia, leading Democrats to today accuse him of lying under oath.

"I will not accept and reject accusations that I have ever lied under oath. That is a lie," Mr Sessions told the panel.

Accusations of collusion with Russia during the election campaign have dogged Trump's first ten months in office.

Mr Sessions' testimony appears likely to keep the controversy over Russia boiling as Special Counsel Robert Mueller accelerates his investigation into possible collusion between the Trump campaign and Russia.

Since Mr Mueller's probe began, numerous Trump advisors have acknowledged interactions with Russian intermediaries.

They include Donald Trump Jr, former campaign manager Paul Manafort, and Mr Trump's son-in-law and senior advisor, Jared Kushner.

Mr Papadopoulos pleaded guilty to lying to the FBI about his interactions with Russian representatives.

US intelligence agencies have concluded that Moscow meddled in the 2016 election to help Republican Trump's campaign.

The Kremlin denies that and Mr Trump says there was no collusion between his campaign and Russian officials.