A former Trump campaign communications adviser will testify next month before the House Intelligence Committee for its investigation of Russian interference in the 2016 election, according to a report Friday.

The committee, which is probing whether the Trump campaign colluded with Russia, plans to interview Michael Caputo, who once worked in Moscow, in a private session July 14, CNN reported.

"We have agreed to appear voluntarily, without subpoena, before the committee in closed session on Friday, July 14," Dennis Vacco, Caputo's attorney, told CNN.

According to report, Caputo lived in Russia starting a few years after the Soviet Union collapsed and he worked for USAID, the U.S government agency that provides foreign aid.

He said he helped the Russian government create open-election laws and advised the successful re-election campaign of then-Russian President Boris Yeltsin.

After moving back to the U.S., Caputo worked as a consultant for Gazprom Media, a subsidiary of state-owned Gazprom, the Russia energy company.

Caputo has said he would cooperate with investigations in Congress, and the probe conducted by special counsel Robert Mueller.

He has denied any wrongdoing and called the collusion probes a "witch hunt."

Caputo is an ally of another Trump associate, Roger Stone.

Stone will voluntarily testify in a private session July 24 before the House Intelligence Committee to describe his communications last year with Russia-linked hackers and WikiLeaks, which published personal emails stolen from Hillary Clinton's campaign chairman, John Podesta.

Showing the breadth of the committee's investigation, the panel also plans to interview Susan Rice, former President Obama's national security adviser, in a nonpublic session some time before Congress departs for its August recess.

Republicans have been interested in interviewing Rice ever since numerous news outlets reported that she sought the identities of people close to Trump whose communications were captured after the election in surveillance of foreigners by U.S. spy agencies.