One of the BBC's top news executives has resigned in the wake of a damning report into the BBC's decision to drop a Newsnight investigation into Jimmy Savile's sexual abuse.

Stephen Mitchell, the deputy director of news, said he was stepping down to bring his career "to a dignified end", but said he disagreed with the report's criticisms of him.

His exit - as well as the replacement of Newsnight's editor and deputy editor - came as a critical report was published which revealed rivalries and factional in-fighting at the BBC.

The report - prepared by former Sky News executive Nick Pollard - said the decision to drop Newsnight's report into Savile's decades of abuse was "flawed" and plunged the BBC into "chaos and confusion".

It said the BBC's management system "proved completely incapable of dealing" with the issues raised by the axing of the story and "the level of chaos and confusion was even greater than was apparent at the time".

The BBC had been accused of dropping the story in order to protect tribute programmes which had been prepared about the late TV host and DJ, but Mr Pollard concluded this was not the case.

The report was published at the same time as another review, by the BBC Trust, concluded that airing a Newsnight report that led to Lord McAlpine being wrongly named as a paedophile had resulted largely from a failure by members of the team to follow the BBC's own editorial guidelines.

Mr Mitchell was criticised for removing the Savile investigation from a list of the BBC's potentially difficult programmes - known as the "managed risk programmes list". The Pollard Report said the executive "could offer no convincing reason" why he had done so but if it had stayed on the list "some of the issues which have followed might well have been avoided".

BBC Trust chairman Lord Patten said the BBC accepted the review in its "entirety" and evidence would be published, apart from some redactions for "legal reasons". Culture Secretary Maria Miller said the Pollard Report raised "serious questions" about the BBC's editorial and management issues.

The BBC Executive said it would tighten up its procedures for difficult stories and there will be improved guidance and training for journalists about how and when material should be handed to police. And in the longer term, the Executive said that "aspects of the management and culture within BBC news must change".