WASHINGTON (Reuters) - Special Counsel Robert Mueller plans to interview the former spokesman of President Donald Trump’s legal team as part of an investigation into potential collusion between Russia and Trump’s campaign to sway the 2016 U.S. presidential election, according to a source with knowledge of the matter.

FILE PHOTO: Special Counsel Robert Mueller (R) departs after briefing members of the U.S. Senate on his investigation into potential collusion between Russia and the Trump campaign on Capitol Hill in Washington, U.S., June 21, 2017. REUTERS/Joshua Roberts/File Photo

Mark Corallo had represented Trump’s outside lawyers amid the federal and congressional Russia inquiries until he resigned last summer, after revelations about a June 2016 meeting between Trump’s son Donald Jr and a group of Russians.

The Mueller team said they wanted to discuss the circumstances of his departure, and the interview was expected within two weeks, according to the source.

Corallo’s departure in July came amid media reports that Trump’s legal team was reorganizing and considering ways to limit Mueller’s probe.

One of the main reasons Corallo decided to leave was his refusal to criticize the integrity of Mueller, the person, who had direct knowledge of the matter, told Reuters.

Corallo was also deeply disturbed by what he viewed as a false statement dictated by president from Air Force One about his son’s Trump Tower meeting with Russian lawyer Natalia Veselnitskaya and her associates, the source said.

The Russians had promised Trump Jr damaging information on Democratic presidential rival Hillary Clinton.

The New York Times on Wednesday reported that Corallo plans to tell Mueller about a conference call last July during which White House adviser Hope Hicks told the president that emails written by Trump Jr “would never get out.”

Citing three people with knowledge of the interview request, the Times said Corallo was concerned about the possibility Hicks could have been planning to obstruct justice.

A lawyer for Hicks strongly denied Corallo’s allegations.

Robert Trout told Reuters in an email: “She never said that. And the idea that Hope Hicks ever suggested that emails or other documents would be concealed or destroyed is completely false.”

The White House did not immediately respond to a request for comment.

U.S. intelligence agencies have determined that Moscow worked to sway last year’s election towards Trump. Moscow has denied interference and Trump, a Republican, has said there was no collusion.

Mueller’s team is investigating whether there was any collusion between Moscow and the Trump campaign, or attempts by members of the Trump team to obstruct the investigation.

Corallo did not want to engage in or be associated with White House attacks on Mueller and top Justice Department officials, according to a person familiar with the matter.

In a July 2017 interview with the New York Times, Trump lashed out at his attorney general, Jeff Sessions, for recusing himself from overseeing the Russia investigation, which led to the appointment of a special counsel. He also attacked Mueller’s investigators as having conflicts of interest, and expressed unhappiness with the deputy attorney general, Rod Rosenstein.

Mueller, a former FBI director, was appointed in May to lead the federal investigation, which so far has resulted in guilty pleas from former Trump national security adviser Michael Flynn and former campaign aide George Papadopoulos. Former campaign manager Paul Manafort and aide Richard Gates have pleaded not guilty to charges that include money laundering.

U.S. Senator Dianne Feinstein, the top Democrat on the Senate Judiciary Committee, one of three congressional panels investigating Moscow’s activities during the campaign, has asked Corallo for an interview next month.