George Entwistle has been roundly criticised for a BBC report which wrongly implicated the former Tory treasurer Lord McAlpine in child abuse.
Speaking on Radio 4 on Saturday, the director general tried to assuage the growing criticism, describing the Newsnight report on the North Wales children's home scandal as "unacceptable", adding that it should never have been broadcast.
He warned that staff involved in the programme shown last week could now face disciplinary action.
However, Entwistle was given a mauling by the show's presenter John Humphries for not taking a closer interest in the programme, particularly on the back of the Jimmy Savile scandal, which included a decision to drop a Newsnight investigation exposing the late DJ as a serial child abuser.
Entwistle said: "We should not have put out a film that was so fundamentally wrong. What happened here is completely unacceptable.
"I have taken clear and decisive action to start to find out what happened and put things right."
He said that he expected a report into what went wrong, being carried out by the director of BBC Scotland Ken MacQuarrie, to be on his desk by Sunday.
"Further action will follow from that - disciplinary if necessary."
Although the programme did not name Lord McAlpine, the peer has indicated that he now intends to sue the BBC after it led to him being identified on the internet.
Entwistle insisted however that he had no intention of resigning, although he accepted that his future now lay in the hands of the BBC Trust.
LISTEN: Audio below of Entwistle's Today interview
"I am doing the right things to try and put this stuff straight. I am accountable to the Trust in that endeavour. If they do not feel I am doing the right things, then obviously I will be bound by their judgment," he said.
Entwistle said that despite the storm over the dropping of Newsnight's Savile investigation, he had not been alerted that the programme was planning a report on the North Wales children's home scandal.
He said that he had also been unaware of a tweet 12 hours before the programme was broadcast, from the Bureau of Investigative Journalism - which worked on the report - suggesting it was going to identify a senior political figure.
"I didn't see that tweet. This tweet was not brought to my attention so I found out about this film after it had gone out," he said.
"In the light of what has happened here I wish this was referred to me, but it wasn't. I found out about the film the following day."
That proved too much for Humphrys, who barked at BBC's editor-in-chief: "So there is no natural curiosity, you wait for somebody to come along to you and say 'Excuse me director general, but this is happening and you may be interested'?"
"You don't look for yourself, you don't do what everybody else in the country does, read newspapers, listen to everything that's going on and say 'What's happening here?'"
Entwistle said that he only became involved if a programme was referred to him for his attention.
He said that Mr MacQuarrie needed to establish why things had gone so badly wrong on Newsnight, despite the appropriate referrals having been made.
"From the inquiries I have been able to make so far, this was a piece of journalism referred to senior figures within news, referred up to the level management board, and had appropriate attention from the lawyers," he said.
Among the issues that needed to be established was whether the abuse victim, Steve Messham, was actually shown a photograph of Lord McAlpine, and whether the peer was given a chance to respond to the allegations.
"Did the journalists carry out basic checks, did they show Mr Messham the picture, did they put allegations to the individual, did they think of putting allegations to the individual, if they did not, why not, and did they have any corroboration of any kind?" he said.
The BBC last night issued an unreserved apology after one of the victims the programme spoke to admitted he had wrongly identified Lord McAlpine as the man who abused him in the 1970s and 1980s.
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