The allegations, made in a Newsnight report on Friday, led to frantic speculation on social-media sites such as Twitter about the identity of the man, who is said to have sexually abused boys from children's homes in Wales. One politician's name appeared prominently in internet speculation.
Twitter users also attacked the BBC – which has been accused of covering up a previous Newsnight investigation into allegations that Jimmy Savile abused children – for prompting rumours and speculation about innocent public figures.
The furore erupted as claims emerged about Rising Damp star Leonard Rossiter, who died in 1984. He has become the latest BBC star to be accused of sex offences, with allegations he was involved in an attempted male rape at Television Centre in the late 1960s
The alleged victim, then an 18-year-old extra on the set of a television play called The Year Of The Sex Olympics, accused Rossiter of performing a sex act on himself while three other BBC staff tried to rape the young man.
However, Radio 4 presenter Jonathan Dimbleby yesterday claimed there was a "witchhunt" against the corporation.
Dimbleby said: "I think it's disgraceful and horribly out of proportion to hound everyone at the BBC in a way that is unwarranted and lacks perspective when the real focus should be on what Savile did wrong.
"Paedophilia is a huge national problem that no-one thought about 50 years ago and is now something that concerns everyone, but this has become a witchhunt against the BBC."
He added: "Organisations that have come under flak recently such as newspapers and MPs want to get their revenge. They think the BBC is too smug and holier-than-thou.
"But there is a disturbing relish in the way the critics have laid into the BBC, holding today's office-holders to account for what happened 30 years ago."
Steven Messham, one of hundreds of children abused over two decades at children's homes in North Wales in the 1970s and 1980s, told Newsnight he was raped more than a dozen times by the as-yet-unnamed senior political figure.
He said: "We were taken by car, where basically we were just sexually abused. Various things would happen, drink would be involved. It was basically rape.
"But there wouldn't be just him (the Tory politician), others would be involved as well."
The Newsnight broadcast claimed the evidence gathered was, for now, "not enough to name names".
Meanwhile, a former headteacher at a girls' school where former pupils claim they were abused by Savile described some of the alleged victims as "delinquents" who were "looking for money".
However, Margaret Jones admitted she had been "hoodwinked" by Savile, and had let him stay overnight at Duncroft Approved School in the 1970s. She claimed no-one had ever reported abuse to her.
She said: "They had an opportunity to tell anybody. But it suited them – some of them, not all of them – to wait 30 years. They're all looking for money. They come out of the woodwork for money.
"I do object to my school being targeted ... [by] wild allegations by well-known delinquents."
At the time of the allegations, the school was run by Barnardo's. The children's charity told police it had no record of any sexual abuse reported to staff.
However, former pupils at the residential school have said they did report Savile's abuse, only to be dismissed by Miss Jones.
Allegations linked to three former residents were also made in 2007.
Jones added: "I was hoodwinked by Jimmy Savile. I thought he was a nice man. Not one person ever told me about Jimmy Savile. Nobody told me he was a pervert. I've just been talking to one of my [former] staff. We are horrified."
"If they didn't tell me about Jimmy Savile, they deserve all they get. They should've reported him. They knew if they reported him to me I'd report him to the police. And I have reported people to the police."
On Friday, comedian Freddie Starr, 69, was released on bail for a second time after being questioned by police investigating the abuse scandal. His arrest followed that of Gary Glitter last Sunday.