US President Donald Trump was "not aware of and did not attend" a 2016 meeting between his son Donald Trump Jr and a Kremlin-connected lawyer who was offering damaging information on then Democratic rival Hillary Clinton, his lawyers say.

Key points: Donald Trump has denied knowledge of the meeting between his son, son-in-law and then-campaign manager Paul Manafort

Donald Trump has denied knowledge of the meeting between his son, son-in-law and then-campaign manager Paul Manafort Donald Trump Jr told the New York Times Ms Veselnitskaya had "no meaningful information"

Donald Trump Jr told the New York Times Ms Veselnitskaya had "no meaningful information" Reports come as Mr Trump faces criticism over plans to build a cyber security unit with Russia

Mr Trump's then-campaign chairman, Paul Manafort, and his son-in-law Jared Kushner also attended the meeting with Russian lawyer Natalia Veselnitskaya at Trump Tower on June 9 last year, two weeks after Mr Trump won the Republican nomination, the New York Times reported, citing three advisers to the White House.

Donald Trump Jr acknowledged the meeting, but said Ms Veselnitskaya had "no meaningful information".

"After pleasantries were exchanged, the woman stated that she had information that individuals connected to Russia were funding the Democratic National Committee and supporting Ms Clinton," Mr Trump Jr said in a statement.

"Her statements were vague, ambiguous and made no sense. No details or supporting information was provided or even offered.

"It quickly became clear that she had no meaningful information."

Mr Trump Jr said he was asked to attend the meeting "with an individual who I was told might have information helpful to the campaign" at the request of an acquaintance he knew from the 2013 Miss Universe pageant.

"I asked Jared and Paul to attend, but told them nothing of the substance," he said.

"The meeting lasted approximately 20 to 30 minutes.

"As it ended, my acquaintance apologised for taking up our time.

"That was the end of it and there was no further contact or follow-up of any kind. My father knew nothing of the meeting or these events."

Donald Trump's son-in-law Jared Kushner is also reported to have attended the meeting. ( Reuters: Kevin Lamarque )

Mr Kushner, who is married to Mr Trump's daughter Ivanka, was the subject of reports in May claiming he had proposed a secret line of communication between the Kremlin and the Trump transition team during a meeting with Russian ambassador to the US Sergey Kisylak in December.

Allegations of the Trump campaign's ties to Russia have cast a shadow over Donald Trump's first five months in office, distracting from attempts by his fellow Republicans in Congress to overhaul the US healthcare and tax systems.

The Kremlin has denied US intelligence agencies' conclusion that Moscow tried to tilt the election in Mr Trump's favour, using such means as hacking into the emails of senior Democrats.

Special Counsel Robert Mueller is investigating the matter, including whether there may have been any collusion on the part of Trump campaign officials, as are congressional committees including both the House and Senate intelligence panels.

Mr Trump has repeatedly denied any collusion.

The revelations about Mr Trump's son comes as the President faced harsh criticism from his own party over a potential plan to form a cyber security unit with Russia.

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Commenting on his first meeting with Russian President Vladimir Putin at the G20 on Friday, Mr Trump sent a series of tweets saying "Putin & I discussed forming and impenetrable Cyber Security unit [sic]".

Mr Trump said "it is time to move forward in working constructively with Russia" and that he had "strongly pressed" Mr Putin twice over Russian election meddling during their meeting.

"It's not the dumbest idea I have ever heard but it's pretty close," Republican Senator Lindsey Graham said.

ABC/wires