The U.S. Vice President indicates that he is not aware of Donald Trump Jr.'s meeting with a Russian lawyer, which critics say suggests intent to collude.

United States Vice President Mike Pence on Tuesday sought to distance himself from the snowballing scandal over possible collusion with Russian election interference that increasingly threatens President Donald Trump.

After Trump's son Donald Jr. admitted to meeting a Russian lawyer offering dirt on Democratic rival Hillary Clinton last June, Mr. Pence declared in a statement that he knew nothing of the meeting — which took place well before he became Trump's running mate in the election.

"The Vice President is working every day to advance the president's agenda, which is what the American people sent us here to do," his office said in a statement.

"The Vice President was not aware of the meeting. He is not focused on stories about the campaign, particularly stories about the time before he joined the ticket."

Also Read Trump Jr. admits he wanted info on Hillary Clinton from Russian lawyer

Earlier on Tuesday, Trump Jr. released emails showing he had arranged to meet with Kremlin-linked lawyer Natalia Veselnitskaya over her offer of "incriminating" material on Hillary Clinton ostensibly sourced from the Russian government. Trump campaign chairman Paul Manafort and the president's son-in-law Jared Kushner also attended the meeting.

Trump Jr. said Ms. Veselnitskaya ultimately had "no meaningful" information on Clinton and instead wanted to talk about US sanctions on Russia. He labelled it a "nonsense meeting”.

But critics say the meeting suggests the Trump campaign was prepared to collude with Russian efforts, not clearly understood at the time, to undermine Ms. Clinton's run for president.

The meeting took place on June 9, five weeks before Mr. Pence was officially chosen as Trump's vice presidential running mate.