According to Thurlbeck, reporters were told by those in "deepcarpetland" to obtain evidence of affairs or gay relationships. The aim, he claimed, was to "find as much embarrassing sleaze on as many members as possible in order to blackmail them into backing off from its highly forensic inquiry into phone hacking".
In a letter to Sue Akers, the Deputy Assistant Commissioner leading the Met's inquiries into News International, Watson wrote: "If these allegations are found to be true, it suggests there was a conspiracy to blackmail."
Watson, a member of the committee put under surveillance by News International, said: "I have evidence that I was put under covert surveillance in September 2009 by the private investigator Derek Webb, as well as Mazher Mahmood and an accomplice.
"Mr Thurlbeck may not be aware of this. I would, therefore, urge you to investigate Mr Thurlbeck's claims in order to establish whether any offence was committed."
The Met launched an inquiry into alleged computer hacking at the Times this year in response to a letter from Watson. Yesterday the Met said it was unable to comment on the MP's latest request. The Leveson Inquiry has been investigating the power wielded behind the scenes by News International.
While blackmail would be a significant deepening of the criminal inquiries, former News of the World reporters have spoken in the past about their use of "leverage" to secure the co-operation of people about whom the paper had embarrassing information.
Thurlbeck, the former chief reporter, disclosed the alleged operation against MPs in comments to Watson that the MP included in his co-authored book, Dial M for Murdoch.
Thurlbeck said that an "edict" had been passed to reporters to "find out every single thing you can about every single [committee] member: who was gay, who had affairs, anything we can use".
Thurlbeck, arrested on suspicion of phone hacking, remains on police bail. News International made no comment on Watson's letter.
- Independent
