Beleaguered business lobby group the Confederation of British Industry (CBI) said it had informed the police of a 'serious criminal offence' and called for anyone with further information to come forward.
The announcement comes weeks after it launched an investigation into alleged widespread misconduct by several senior figures.
Earlier this month, The Guardian reported that a dozen women had made complaints of sexual harassment with one allegation of rape at a staff party in 2019.
The complainant was reportedly told to get counselling rather than pursue it further, with no contact made with the police.
CBI director-general Tony Danker, who was already under scrutiny after a sexual harassment allegation, was fired last week.
On Wednesday, he said in an interview that his reputation had been “totally destroyed” and he had been tarred by incidents that occurred before he took charge.
The CBI said it expects a report “imminently” from Fox Williams, the law firm appointed to carry out its investigation.
This latest allegation is a new incident that had not been reported previously, the CBI said.