A Russian lobbyist who attended a meeting between President Trump campaign officials and a Russian lawyer has testified before special counsel Robert Mueller's grand jury, The Financial Times reported Wednesday.

Rinat Akhmetshin, a former Soviet army officer, testified before the jury for several hours on Aug. 11, signaling that Mueller is including the controversial Trump Tower meeting in his investigation.

Mueller convened a grand jury earlier this month as part of his investigation into Russian interference in the U.S. presidential election.

Akhmetshin was part of the controversial 2016 meeting that came to light last month, during which Donald Trump Jr., along with campaign head Paul Manafort and White House senior adviser Jared Kushner, met with Russian lawyer Natalia Veselnitskaya.

Trump Jr. has denied any wrongdoing in taking the meeting.

One of the emails sent by Rob Goldstone, the man who helped set up the meeting, promised the lawyer had information that "would incriminate [Democratic nominee] Hillary [Clinton] and her dealings with Russia and would be very useful to your father."

"This is obviously very high level and sensitive information but is part of Russia and its government's support for Mr. Trump," Goldstone wrote.

"If it's what you say I love it especially later in the summer," Trump Jr. replied.