The BBC antisemitism row has deepened after a board member with links to the government questioned editors about the corporation’s coverage of an attack on Jewish passengers on a London bus.

Newsroom sources say that Sir Robbie Gibb, who was Theresa May’s communications director, raised concerns about the BBC’s reporting on the Oxford Street incident last year.

One insider said that Gibb had been conducting his own inquiry into the case before the intervention last Friday by Nadine Dorries, the culture secretary, and Ofcom, the media regulator.