BBC director general George Entwistle has resigned over a television report that wrongly implicated a former senior Conservative party figure in child sex abuse allegations.
Earlier, Mr Entwistle said the item on the Newsnight programme that incorrectly implicated former Conservative Party treasurer Lord McAlpine should never have been broadcast.
Mr Entwistle had issued a full apology to Lord McAlpine, who, while not named in the report, was wrongly identified on the internet as the alleged abuser at children's homes in Wales in the 1980s.
On Friday, Lord McAlpine went public to rigorously deny the allegations and threaten legal action.
Abuse victim Steve Messham, who was a witness in the Newsnight report, also apologised and said the Tory peer was not the man he'd identified to police in the 1990s as having assaulted him.
In a statement, Mr Entwistle said that in the light of the unacceptable journalistic standards of the Newsnight film he had decided the honourable thing to do was to step down from the post of director general.
The BBC and its bosses have been under huge pressure since a rival broadcaster carried charges last month that a former BBC star, the late Jimmy Savile, was a prolific sex offender, Reuters reports.
To complicate matters for Mr Entwistle, Newsnight pulled a planned expose of Savile shortly after his death last year, and the BBC went ahead with tribute shows.
On Saturday Mr Entwistle, who took up the role on 17 September, admitted under questioning from his own journalists that he had not known in advance about the 2 November Newsnight report, weeks after being accused of being too hands-off over the previous scandal on the same programme.