The BBC has announced a "freestanding investigation" into how disgraced TV star Stuart Hall was able to abuse his victims while working for the corporation.

The fact-finding mission will feed into Dame Janet Smith's Jimmy Savile inquiry, but will be led by a "different individual" because of a "potential conflict of interest".

A BBC spokesman said: "In light of a potential conflict of interest with Dame Janet Smith there will be a freestanding investigation covering Stuart Hall's conduct at the BBC. This work will be led by a different individual appointed by the BBC."

The potential conflict of interest has arisen because Dame Janet knows Ray Colley, who worked with Hall at the BBC studios in Manchester.

Hall, 83, has admitted indecently assaulting 13 girls during the 1960s, 70s and 80s, including one aged nine.

The chairman of the BBC Trust Lord Patten admitted the corporation was likely to face compensation claims from Hall's victims. Asked whether the BBC would be liable, he said: "I imagine so, but that will be a matter for the lawyers and conceivably the courts.

"I think it would be incredible to be able to do that (estimate the cost of compensation) now because first of all what needs to happen is that we need to be able to get a grip on what happened and of course, in the meantime, co-operate with the police. It's a different case from the Savile case because the main person who is alleged to have committed these crimes – who has committed these crimes, he has owned up to some of them – is actually alive."

He added: "If we need to do more, we will."

Hall faces a possible jail sentence and was described as an "opportunistic predator" after he appeared at Preston Crown Court.