The theater said it received 20 personal complaints of inappropriate behavior by Spacey during his time as director. It said numerous alleged incidents took place at the theatre - located in the borough of Lambeth - and involved members of staff. "Officers from the Child Abuse and Sexual Offences Command are investigating".
"On Friday, 17 November, a further allegation was made about the same man".
But the allegation is dated back to 2005 in Lambeth, the borough of London where the theater is located.
The theatre launched an investigation into its former leader last month after American actor Anthony Rapp alleged that Spacey had climbed on top of him on a bed when Rapp was 14 and Spacey 26.
"The allegations are of sexual assaults against a man in 2005 in Lambeth".
They did however confirm that the allegations were made by a man in Lambeth.More news: 'CBS This Morning' to air for 1st time after Rose suspension
In response to the claims, Spacey issued a post on Twitter in which he wrote that he did not remember the alleged incident and also announced he is living as a gay man.
Netflix and Sony Pictures have cut ties with the star, firing him from House Of Cards and replacing him in upcoming film All the Money in the World.
The Old Vic apologised "for not creating an environment or culture where people felt able to speak freely". He has denied allegations of assault, but said he is now seeking "evaluation and treatment" of his behavior.
Kate Varah, the Old Vic's executive director, issued an apology on November 16 to the alleged victims.
A man on the east coast of the U.S. said that Spacey repeatedly had sex with him when he was 14, adding: "He tried to rape me".