London, Apr. 14 : A humiliated British Prime Minister Gordon Brown voiced “great regret” last night over his key aide Damian McBride’s sick plot to smear top Tories, but refused to apologise.

With a successful G-20 summit under his belt, Brown was hoping next week’s Budget would boost his dismal showing in the polls, but instead, he was engulfed by strategy chief McBride’s putrid conspiracy to smear top Tories.

Brown was forced to spend yesterday sending “personal” letters to the victims of this appalling plot — David Cameron, George Osborne and MP Nadine Dorries, reports The Sun.

The PM also ordered tough new rules for Labour’s army of spin doctors. But he stopped short of issuing the full, personal apology demanded by the Conservatives.

On the McBride emails, Brown said: “Any activity such as this that affects the reputation of our politics is a matter of great regret to me and I am ready to take whatever action is necessary to improve our political system.”

He insisted that he was satisfied “no minister and no political adviser” was involved in the chilling plot apart from McBride — who was the PM’s strategy chief.

Last night a spokesman for Mr Cameron said: “David Cameron welcomes the Prime Minister’s letters and the fact that he has finally recognised the gravity of what has been happening in Downing Street.” (ANI)