WASHINGTON (Reuters) – U.S. President Donald Trump’s former personal lawyer Michael Cohen said that Trump knew in advance about a June 2016 meeting in Trump Tower at which Russians offered to provide damaging information about his Democratic rival Hillary Clinton, CNN reported on Thursday.

CNN, citing unnamed sources with knowledge of the matter, said Cohen is willing to make that assertion to Special Counsel Robert Mueller, who is investigating possible collusion between the Trump campaign and Russia during the U.S. 2016 presidential campaign.

“He cannot be believed,” Rudy Giuliani, a lawyer for Trump, told Reuters on Thursday, referring to Cohen. “If they rely on him … it would destroy whatever case they have.” Giuliani was referring to Mueller’s investigation.

Cohen did not immediately respond to a request for comment from Reuters. His attorney Lanny Davis declined to comment.

Peter Carr, a spokesman for Mueller, declined to comment. Nicholas Biase, a spokesman for Manhattan federal prosecutors, also declined to comment.

Federal prosecutors in New York are investigating Cohen for possible bank and tax fraud, and for possible campaign law violations linked to a $130,000 payment to adult film star Stormy Daniels, who has claimed she had a sexual encounter with Trump, and other matters related to Trump’s campaign, a person familiar with the investigation has told Reuters.

Cohen has not been charged with any crime. Trump has denied having had an encounter with Daniels.