Jimmy Savile sex abuse described as 'a dark chapter in the history of the BBC'

And he vowed that the review into its culture would be "invaluable" in helping to ensure such incidents never happen again.

A leaked draft report of the review by Dame Janet Smith condemns the BBC over its "deferential culture" and "untouchable stars", and criticises it for having managers who were "above the law".

• Read: Leaked Jimmy Savile report: Incidents took place in Glasgow

It also warns that it was possible another "predatory child abuser could be lurking undiscovered in the BBC even today".

Rapes, indecent assaults on both boys and girls, and incidents of "inappropriate sexual conduct" with teenagers over the age of 16 were all "in some way associated with the BBC", the draft report states, adding that three of Savile's victims were only nine.

Incidents occurred at "virtually every one of the BBC premises" in which Savile worked, the report said, and more than 100 employees at the corporation told the review they had heard about Savile's sexual conduct.

Commenting after the leaked report, Lord Hall said: "Firstly, my thoughts and all our thoughts are with the victims of Jimmy Savile and their families. What happened was a dark chapter in the history of the BBC.

"Dame Janet Smith's report will be invaluable in helping us understand what happened and to help ensure that we do everything possible to avoid it happening again.

"The review has said that the copy leaked to the media is an early draft which has changed considerably, so, while I am impatient to learn those lessons, the responsible thing must be to act on the final report, which we have not received."

Savile was found to have carried out four rapes - two of girls under 16 - and one attempted rape, which were among 61 incidents of sexual assault.

Abuse took place on the sets of Top Of The Pops and Jim'll Fix It, at least once on camera, as well as in corridors, kitchens, canteens and dressing rooms at the BBC Television Theatre, Television Centre and Broadcasting House, where Savile worked for Radio 1.

Others incidents occurred at the Lime Grove studios in London and BBC properties in Leeds, Manchester and Glasgow.

But while staff said they were aware of his sexual behaviour, they were scared to report it to managers, the draft report, published by news website Exaro, states.

Investigations into allegations of sexual assault were "wholly inadequate", and the BBC was criticised for failing to properly examine his personality, despite rumours about him and that he worked with children.

But retired judge Dame Janet accepted denials from senior bosses that they were aware of his sexual activity, according to the leaked document, and she does not criticise the BBC for not discovering the abuse.

While there were "several factors, incidents and conversations" that together pointed to a potential problem with the broadcaster, "I do not think the BBC can be criticised for failing to uncover Savile's sexual deviancy", Dame Janet writes.

She adds that no senior BBC staff were ever aware of information which could have "led to, or assisted in, the prosecution of Savile", and that "prosecution and imprisonment" was the only way to stop him.

But she does condemn the BBC for its culture, according to Exaro, saying: "My general impression is that most staff (other than those who had been in the higher echelons) felt that the management culture was too deferential and and that some executives were 'above the law'."

The BBC's "talent" was held in "awe" by most staff, who treated them "deferentially", she said, adding: "It would be a brave person indeed who would make a complaint against such a person."

Liz Dux, a specialist abuse lawyer at Slater and Gordon, which represents 168 alleged Savile victims - many of whom where assaulted at the BBC - said: "It is deeply disturbing that this inquiry appears to have concluded the same culture which allowed Savile to commit his appalling offences with impunity still persists today.

"That little has been done at the BBC to prevent another predatory abuser using their celebrity and influence to target the young and vulnerable is of grave concern.

"I find it incredible that 107 people gave evidence to having heard rumours of his depravity and inappropriate sexual behaviour yet no-one in a position of authority seemed to be aware.

"Now, more than ever before, mandatory reporting legislation needs to be brought in to make it a crime to turn a blind eye to this sort of offending.

"It also has to be said that Savile's victims who gave evidence to this inquiry will find it upsetting that a report of this nature and sensitivity has been leaked in this way."

A statement on the Dame Janet Smith Review website expressed disappointment at the leak of the draft but said it was out of date.

It said: "The review is disappointed by the decision of Exaro to publish, in breach of confidence, extracts from a leaked copy of an early draft of its report.

"That document is out of date and significant changes have been made to its contents and conclusions.

"The document should not have been made public and cannot be relied upon in any circumstances.

"The review will work with the BBC to arrange publication of its final report as quickly as possible to ensure that accurate and responsible reporting can take place."

The leaked draft was published a day after the review announced that the long-delayed final report would be published within six weeks.

It said this was because "the review has been informed by the Metropolitan Police that it is no longer concerned that publication of the report could prejudice its ongoing investigations".

It said final checks were being carried out ahead of delivery to the BBC and publication. Drafts of the report will have been seen by numerous parties involved in the review.

BBC Trust chairman Rona Fairhead said the review dealt with "very troubling issues" and the corporation was grateful to those who had come forward.

She said: "As the review has said today's media reports result from a leaked copy of an early draft which cannot be relied upon, it would be premature to comment until we have seen the review.

"We will provide every possible assistance to enable swift publication, and make sure the BBC takes all appropriate action to address the report's conclusions."

Jesse Norman, chairman of the Culture, Media and Sport Committee, said if the leaked draft mirrors the final report, it is a "terrible indictment" of the culture of the BBC at the time.

He told BBC Radio 4's World At One: "I think it's very likely we will want to talk to senior figures at the BBC about the extent to which the culture has changed now and potentially other members because the public needs to be satisfied that the culture has changed."

Read: Jimmy Savile carried out four rapes at BBC, say leaked draft of Smith report