The BBC is to begin disciplinary measures against staff involved in a Newsnight investigation which wrongly accused a Tory MP of child abuse after it concluded there had been "unacceptable" editorial failings.
The Newsnight investigation falsely accused a "senior Conservative" MP, widely believed to be Lord McAlpine, of abusing children at the Bryn Estyn care home.
The claims were later completely dismissed after the accuser Steve Messham apologised to McAlpine when he realised he was the victim of "mistaken identity".
A BBC report into the programme, conducted by the broadcaster's Scotland director Ken MacQuarrie, concluded that "some of the basic journalistic checks were not completed" before the programme was broadcast.
Peter Johnston, the director of BBC Northern Ireland, is one of the people expected to face disciplinary measures after the BBC confirmed he was involved in decisions about the BBC Newsnight report.
Liz Gibbons, the programme's acting director, and supervising executive Adrian Van Klaveran are also expected to face disciplinary measures.
The report said Newsnight's editorial management had been "seriously weakened" after the show's editor Peter Rippon "stepped aside" from his role following the dropped investigation into Jimmy Savile, which also prompted the departure of one of Newsnight's deputy editors.
It also condemed the fact that McAlpine was also offered no "right of reply" to the accusations as they did not have enough evidence to name him, although legal advice was sought, and a photo of McAlpine was never shown to his accuser.
In his report, MacQuarrie said: "During the editorial decision-making process, some of the basic journalistic checks were not completed.
"Specifically, identification was not confirmed by photograph with the first victim. The second victim could not be traced in order to provide up-to-date corroboration."
When asked at a conference in Salford why Messham was not shown a picture of McAlpine, Van Klaveren said: "I don't think this is the right place to get into the detail, there is obviously a lot of detail to get into."
A spokeswoman said: "It is clear from the MacQuarrie report on the November 2 Newsnight that there were serious failures in the normal checks and balances that the trust expects from BBC journalism, and these were compounded by the confusion created by the dual reporting structure in news established during the Pollard inquiry. This is very concerning."
The case of mistaken identity led to the resignation of the BBC's director general George Entiwslte after just 54 days in office for what the report described as "unacceptable" failings.
The BBC has received extra criticism after it emerged Entwislte will receive a £450,000 pay-off following his resignation, twice the amount specified in his contract.
Prime Minister David Cameron's official spokesman described the pay-off as "hard to justify".
Acting director general Tim Davie has vowed to "get a grip" of the situation, although he has faced criticism for walking away from an interview with Sky News presenter Dermot Murnaghan and failing to answer the question "are more heads going to roll?"
A BBC spokesman said Davie did not walk out of the interview, but left because it had overrun and he had to give other interviews elsewhere.