Tom Watson, the deputy chairman of the Labour Party, said there is “clear intelligence” a Number 10 aide was connected to Peter Righton, who was convicted of importing child pornography in 1992.
Mr Watson, who led calls for phone-hacking to be investigated, urged police to examine the historic allegations but would not name the aide or who was in Downing Street at the time.
His call comes amid public outrage the BBC, schools and hospitals failed to act on allegations that Jimmy Savile abused children on their premises in the 1960s and 1970s.
Police are now investigating more than 200 claims that Savile indecently assaulted teenagers, after a two-year investigation into the television presenter was dropped in 2009.
Mr Watson said he had recently been contacted by a child protection expert alleging that Righton’s paedophile ring had also not been fully investigated.
“The evidence file used to convict Peter Righton, if it still exists, contains clear intelligence of a widespread paedophile ring,” he told MPs.
“One of its members boasts of his links to a senior aide of a former prime minister, who says he could smuggle indecent images of children from abroad.
“The leads were not followed up, but if the files still exist, I want to ensure that the Metropolitan Police secure the evidence, re-examine it and investigate clear intelligence suggesting a powerful paedophile network linked to Parliament and No 10.”
Writing later on his blog, Mr Watson said the Downing Street aide was not the late Sir Peter Morrison, the former MP named at the weekend by Edwina Currie as having had inappropriate relationships with teenage boys.
David Cameron said it was a “very difficult and complex case” and he was “not entirely sure” to which former prime minister Mr Watson was referring.
The Prime Minister said he would look at the case “very carefully and see what the Government can do to help give” Mr Watson the assurances he wanted.