Young footballers were targeted for years at Chelsea by a "prolific and manipulative sexual abuser" who was able to operate "unchallenged", according to a damning report.
Evidence from 23 victims details how former chief scout Eddie Heath groomed and abused young boys aged between 10 and 17 during the 1970s.
An external review concluded that some adults at Chelsea must have been aware of the sexual abuse by Heath, who died in 1983, but "turned a blind eye to what they saw".
In a statement, Chelsea's board apologised "unreservedly" and said Heath's "abuse was able to occur unchallenged".
The report - led by barrister Charles Geekie QC - is also heavily critical of former assistant manager Dario Gradi, who is accused of failing to tell more senior club staff about an allegation regarding the sexual conduct of Heath, brought to him by the parent of a young player.
Gradi's failure to report the allegation "was a lost opportunity to expose Heath and prevent further abuse".
The BBC has approached Gradi for comment. In his evidence to the review, he denied trying to "smooth over" the matter in a meeting with the boy's father. He also said he reported the allegations to the club's assistant manager.
Meanwhile, a separate review into allegations of racial abuse from 1982 up until the late 1990s conducted by charity Barnado's concluded that "black players were subjected to a daily tirade of racial abuse"