Paul Merton, the comedian and star of TV current affairs comedy show Have I Got News For You, admitted he did not suspect Jimmy Savile was a paedophile when he appeared on a controversial show in 1999.

Savile, since revealed to be a serial abuser of children and women, appeared on a particularly uncomfortable edition of the show, which also stars Ian Hislop.

Merton, appearing at the Edinburgh International Book Festival to talk about his memoir, Only When I Laugh, was asked by a member of the audience what he thought of the late DJ and paedophile's appearance on the show.

"This was back in 2000 [actually 1999]. Often people appear on the show and you don't know why they have come on the show," he said.

"And I don't know why he came on the show. Back in those days, nobody in the studio believed he was a paedophile - I didn't.

"My thinking was, which I think would be a lot of people's thinking, was 'How can he be?' I didn't know anything about how he operated.

"'How can he be?' He is the most recognisable man in Britain, how could he possibly be doing this stuff without people saying: 'That's the man'.

"I didn't know that the victims weren't going to be believed, I didn't know the police forces were doing what they were doing, that he was a friend of Thatcher and all this stuff to make himself particularly invulnerable.

"He was a strange guy, but this other stuff wasn't known. People said all kinds of things, but that wasn't proof.

"I just thought he was a strange, strange guy but I didn't believe the stories I heard."

Merton said that the show has lawyers on set and often times the show is edited and re-recorded on set to avoid legal entanglements.

He added: "There was one man who did sue us, the programme referred to him as a 'little sh*t'.

"He took this to court but the judge ruled in our favour that he was a little sh*t. He threw the case out. I am glad I cannot remember his name".

Merton made light of his relationship with Hislop, who is the editor of Private Eye.

He said Hislop had thought he was his mini-cab driver when they first met.

Merton said Hislop did not know how to react to Bruce Forsyth when he hosted the show.

"When Hislop's family bought their television from Harrods, they had the ITV button removed," he said.

Merton said that the Daily Mirror under editor Piers Morgan had spent a year trying to find "dirt" on Hislop, but had found nothing.

Merton is also appearing in an improvised show at the Pleasance venue as part of the Edinburgh Festival Fringe.

Merton also spoke candidly about his time in psychiatric hospital following a reaction to malaria tablets, where he suffered from manic episodes.