Britain's opposition Labour Party wrote to the head of the BBC on Thursday to complain about its coverage of campaigning ahead of next week's election, accusing the publicly funded broadcaster of bias.

Labour's co-campaign coordinator, Andrew Gwynne, said they had recorded numerous examples where his party's leadership had received "more negative treatment, harsher scrutiny and slanted editorial comment" than Prime Minister Boris Johnson's Conservatives.

"That bias has been reflected in the framing, content and balance of BBC reporting during the campaign," Gwynne wrote in a letter to BBC Director General Tony Hall.