The BBC said on Wednesday it had launched an investigation into how it had failed to edit out a racial slur from its broadcast of Britain's top movie awards.

At the BAFTA Awards on Sunday night, a guest with Tourette syndrome shouted out while two actors from "Sinners", Michael B. Jordan and Delroy Lindo, were on stage.

The BBC broadcast the show around two hours later and the offensive language remained in the programme, and on its streaming platform until Monday morning.

The slur was shouted by John Davidson, who attended the awards in London after his life inspired the film "I Swear".

Davidson said his condition caused his body and voice to act in ways he does not intend. He said he was mortified if anyone considered his involuntary tics to be intentional.

The BBC said it had reviewed what it called a "serious mistake" and would act quickly.

"The Director-General has instructed the Executive Complaints Unit to complete a fast-tracked investigation and provide a full response to complainants," a spokesperson said in a statement.

BAFTA has apologised to the two actors and said it took full responsibility for what happened.