The Conservative Party has strongly denied accusations that it was prepared to "smear" Labour MPs with allegations that they were paedophiles.
On Wednesday, Labour MP Tom Watson suggested that staff at Conservative Campaign Headquarters (CCHQ), formerly known as Conservative Central Office (CCO), were either withholding information from police or inventing "disturbing" stories for political gain.
A Tory party spokesperson said Watson's allegation was "completely false and without foundation".
In a lengthy blog post , Watson said his fellow Labour MP, Chris Bryant, had been tipped off by a Daily Telegraph journalist.
According to Bryant, the Daily Telegraph reporter said he had been "accidentally included in a series of email exchanges between senior figures at Conservative Central Office who were speculating about which Labour sitting MPs were paedophiles and how they should deploy this 'information'."
Bryant told Watson the reporter did not believe the allegations "were anything other than nasty vindictiveness and an attempt to smear Labour MPs".
Watson said "senior offices at CCHQ were either a; holding back vital intelligence from the police abuse inquiry or b; engaging in a smear campaign against their opponents." He added: "Either way, it showed appalling conduct."
The Labour MP also published a letter he sent to David Cameron on January 26 demanding more information. "It is possible that it is a serious piece of investigative work. In which case I urge you to hand this evidence over to the police immediately, so that they can investigate -rather than keeping it in the confines of the party," Watson told the prime minister.
"You recently publicly declared that all documents held by party whips will be made available to the police. I trust the same is true of internal party emails.
He added: "If, however, it is a scurrilous and puerile attempt to smear sitting politicians, then that is a different but no less serious matter."