Russian lawyer Natalia Veselnitskaya, who attended the meeting at which Trump Jr thought he was to get information from the Russian government that would hurt Clinton in the US election campaign, brought along a Russian-American lobbyist who NBC News said had formerly worked for Russian spy agencies.
The unidentified man, who has dual Russian and US citizenship, is "a former Soviet counter intelligence officer who is suspected by some US officials of having ongoing ties to Russian intelligence," NBC News reported.
In the June 9 meeting, Trump Jr has said, Veselnitskaya did not produce damaging information on Clinton after all and instead focused on a sanctions issue that involves a Russian company she represented.
Nevertheless, emails showing he accepted the meeting on that premise and said he would "love" to get dirt on Clinton stoked allegations that the Trump campaign colluded with Russian attempts to influence the election in Donald Trump's favor.
The meeting was also attended by Trump campaign manager Paul Manafort and son-in-law Jared Kushner, underscoring how important the campaign thought the meeting could be.
NBC News said the lobbyist "denies any current ties to Russian spy agencies."
It also quoted Trump Jr.'s lawyer, Alan Futerfas, as saying Trump Jr., who now runs the family real estate business, did not know anything about the man's background at the time of the meeting.
"He is a US citizen. He told me specifically he was not working for the Russian government, and in fact laughed when I asked him that question," said Futerfas.