The FBI is investigating an anonymous woman's claim that she was offered $20,000 to accuse Special Counsel Robert Mueller of sexual assault.
Mueller is investigating allegations that President Trump's campaign colluded with Russia to meddle in the 2016 election. He is also looking into whether Trump attempted to obstruct the probe.
In a rare public statement, Mueller spokesman Peter Carr said Tuesday "when we learned last week of the allegations that women were offered money to make false claims about the special counsel, we immediacy referred the matter to the FBI for investigation."
Carr offered no details of the case which may be an effort to discredit Mueller as the investigation continues.
News outlets say an unknown woman contacted them by email, claiming someone offered her cash to say Mueller sexually assaulted her in the 1970s when they worked together at the FBI.
The woman says the person who contacted her claimed to work for Republican activist and right-wing radio talk show host Jack Burkman.
Burkman calls himself "the victim of a hoax" and that he did not pay anyone.
But he said last week on Facebook and in tweets that he would "reveal the first of Special Counsel Robert Mueller's sex assault victims. I applaud the courage and dignity and grace and strength of my client."