A Panorama documentary is set to plunge the BBC into fresh controversy by claiming it pulled an investigation into the Savile sex abuse scandal after coming under pressure from bosses.

The hour-long documentary lifts the lid on the extent to which the higher echelons of the BBC were aware of the claims against the late DJ.

BBC foreign editor John Simpson describes the scandal as ‘the worst crisis that I can remember in my nearly 50 years at the BBC’.

Newsnight editor Peter Rippon maintains the piece – which was due to run last December – was pulled for editorial reasons, and not because the potentially damaging revelations coincided with a planned tribute to the star.

But tonight (Monday), the hour-long documentary will hear from Newsnight producer Meirion Jones and reporter Liz MacKean, who both claim they had interviewed at least four alleged victims of Savile – and confirmed with Surrey Police that they had investigated sex abuse complaints against the Jim’ll Fix It star in 2007.

They say that when they told bosses the Crown Prosecution Service did not charge Savile because of insufficient evidence, they were told to end the investigation – and the show was withdrawn.

The horror stories about Savile only fully emerged after ITV broadcast a documentary at the start of October, sparking mayhem at the BBC over losing its scoop and leading to allegations of a cover-up.

A Panorama statement said: “Peter Rippon has always maintained the story was pulled for ‘editorial reasons’ and not because of a potentially embarrassing clash with planned BBC tributes to Savile over Christmas. Panorama has found no evidence to contradict that view.”

Simpson said of the fall-out: “This is the worst crisis that I can remember in my nearly 50 years at the BBC. I don’t think the BBC has handled it terribly well.

Panorama, which screens at 10.35pm on BBC One, also probes why BBC chiefs gave different explanations over the nature of the documentary and why it was dropped.