A meeting between Donald Trump Jr. and a Russian lawyer in June 2016 was also attended by a Russian-American lobbyist who was a former Soviet counter-intelligence officer, NBC News reported on Friday.
NBC News did not identify the former intelligence officer, who it said had denied any current ties to Russian spy agencies but had served in the Soviet military. He has emigrated to the United States, where he holds dual citizenship.
Washington this week has been fixated on emails released by President Donald Trump's eldest son showing he met with a Russian lawyer during the 2016 presidential campaign after he was told she might have damaging information about Democratic candidate Hillary Clinton.
The revelation of the meeting would be the most tangible evidence yet of a connection between Trump's campaign and Russia, a subject that has also prompted an investigation by a federal special counsel.
NBC said the lobbyist accompanied the lawyer, Natalia Veselnitskaya, to the meeting at Trump Tower in Manhattan attended by Donald Trump Jr. as well as the president's son-in-law, Jared Kushner, and former campaign adviser Paul Manafort.
Veselnitskaya acknowledged in an exclusive interview that she was accompanied by at least one other man, whom she would not identify, NBC said.
NBC News said representatives for Kushner and Manafort declined to comment, but that a lawyer for Donald Trump Jr. said he had spoken to the lobbyist.
Attorney Alan Futerfas said the man was described as a friend of Emin Agalarov, a Russian pop star who was a client of Rob Goldstone, a music publicist who had arranged the meeting, and possibly of Velenitskaya's, NBC said.
Futerfas said he had talked with the individual who came to the meeting with Veselnitskaya: "He is a U.S. citizen. He told me specifically he was not working for the Russian government, and in fact laughed when I asked him that question.”
Futerfas told NBC that, “for the purpose of security or otherwise, the names were reviewed” but said Trump Jr. knew nothing about the man's background at the time of the meeting.
When asked by NBC about whether he had concerns, knowing what he knows now, Futerfas said: “I have absolutely no concerns about what was said in that meeting.”
NBC said Veselnitskaya denied having any connection to the Kremlin and insisted the meeting was to discuss U.S. sanctions against Russia, not the presidential campaign.
Accusations that Moscow meddled in the election and colluded with the Trump campaign have dominated Trump's first months in office. Russia denies the allegations, and Trump says there was no collusion.
U.S intelligence agencies said earlier this year that Russia sought to help Trump win the election by hacking private emails from Democratic Party officials and disseminating false information online.
Trump told Reuters on Wednesday that he did not know about his son's meeting until recently. But in a conversation with reporters later that day, Trump said: "In fact, maybe (the meeting) was mentioned at some point," adding he was not told it was about Clinton.
The Republican president drew criticism last week from Democrats who accused him of not pressing Russian President Vladimir Putin hard enough at a meeting they held in Germany over Moscow's alleged interference in the 2016 campaign.
Trump said in comments released by the White House on Thursday that he would invite Putin to the White House but added that now was not the right time for that.