DOWNING STREET e-mails setting out plans for a vicious smear campaign against the Tories, which last night forced the resignation of one of the prime minister’s most senior aides, are revealed today.

The e-mails, seen by The Sunday Times, expose how Gordon Brown’s head of strategy and planning wrote to a Labour spin doctor proposing a campaign of unfounded personal slurs against senior Tories. The smears, many of a sexual nature, were planned as part of a strategy to “destabilise” the opposition in the run-up to the general election.

The operation was designed to target David Cameron, the Conservative leader, George Osborne, the shadow chancellor, and three other Tory MPs. The messages from Damian McBride, a long-standing Labour aide, were sent from an official No 10 e-mail address. The unfounded smears suggested: “Putting the fear of God” into Osborne by spreading rumours that he took drugs and had sex with a prostitute. Challenging Cameron to reveal details of an “embarrassing illness”. Accusing a gay Tory MP of promoting his partner’s business interests in the Commons.

McBride’s e-mails were sent to Derek Draper, a former aide to Lord Mandelson and prominent Labour blogger. In an indication of how serious the plan was, McBride wrote about how to “sequence” the stories for maximum impact. The messages discuss “timing and technology” for placing the rumours on the web and contain suggested links to websites and photographs that could make the allegations appear more credible.

The contents of the e-mails, which fell into the hands of Paul Staines, a political blogger, shatter Labour claims yesterday that McBride and Draper were “knocking around ideas” that were merely “juvenile and inappropriate”. At least one of the e-mails was copied to other Labour activists, including Charlie Whelan, who used to work as Brown’s spin doctor.

McBride, who was paid a six-figure salary by the taxpayer, resigned from his post last night as the attempted smear campaign was condemned by politicians from all sides. Labour MPs accused him of disgracing the party. Charles Clarke, the former home secretary, said: “Damian McBride has no place in 10 Downing Street. His actions bring shame to the Labour party.”

The e-mails were sent on January 13. The proposed slurs about Cameron, Osborne, Osborne’s wife Frances and three other Tory MPs, were designed to appear on a website called Red Rag, which McBride suggested should be advertised on LabourList, a website officially backed by the party.

Chris Grayling, the shadow home secretary, said the proposed smear campaign “beggared belief” and demanded an urgent explanation from the prime minister.

Tom Watson, a junior Cabinet Office minister who is referred to in passing in a separate e-mail from McBride to Draper about LabourList, has denied any involvement in the smear campaign.

A Downing Street spokesman said: “The prime minister has accepted Mr McBride’s resignation.”

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