Campaigning MP Tom Watson has vowed he will continue his demands for a full inquiry into child abuse despite coming under fire from critics.

Black Country MP Mr Watson (Lab West Bromwich East) was accused of making “sensationalist” claims by Conservative MP Rob Wilson (Con Reading East), who urged him to stop repeating “unsubstantiated rumours”.

But he insisted: “I will not let this matter drop regardless of what pressure is bought to bear by those that seek to undermine legitimate inquiry.”

His pledge comes as the BBC was plunged into crisis over a report on BBC Two programme Newsnight, which claimed a Conservative politician abused children at a care home in north Wales.

The report led to former Conservative Party treasurer Lord McAlpine being wrongly identified on the internet as the abuser – and the BBC admitting the story was wrong and issuing an unreserved apology.

BBC Director General George Entwistle resigned, along with the BBC’s director of News, Helen Boaden.

Mr Watson last month told the House of Commons he believed there was “clear intelligence suggesting a powerful paedophile network linked to Parliament and Number 10,” involving a “senior aide of a former Prime Minister”.

However, he did not name anyone – nor drop any hint about when this Prime Minister was in office or which party they belonged to. He was not referring to the North Wales care home, but to a separate case involving Midland paedophile Peter Righton, of Evesham, Worcestershire, who is now dead.

In a letter to David Cameron, published on his blog earlier this month, Mr Watson also said he had been told about “alleged child abuse and a former cabinet minister”.

The MP insisted he would not be silenced. Mr Watson said in his reply to Mr Wilson; “My concern is that the institutions that are there to protect vulnerable children may have historically failed. I do not know why this is the case but seek to understand it.”

Mr Watson said he had been approached by a former child protection specialist because: “he felt I was prepared to speak out on a perceived injustice and see it through to the end.”