Tory leader David Cameron has accused the Prime Minister of "desperate" measures to keep a row going over allegations that the shadow chancellor sought a donation for the Tories from a Russian billionaire.
Mr Cameron hit out as he continued to defend George Osborne over claims he tried to solicit a £50,000 donation from aluminium tycoon Oleg Deripaska.
Prime Minister Gordon Brown called for "the authorities" to investigate Mr Osborne's relationship with the Russian billionaire.
But Mr Cameron responded: "I don't understand what he was on about - and I'm not quite sure he did either."
He added: "The Prime Minister's spokesman was asked what needed to be answered, what the allegations are that need to be investigated and there literally was no answer.
"I can only assume it was a desperate measure to try and keep things going with a piece of political manoeuvring."
The affair was kick-started on Tuesday with a letter in The Times from banker Nathaniel Rothschild claiming that Mr Osborne and Tory fundraiser Andrew Feldman sought to solicit the donation when they visited Oleg Deripaska's yacht in Corfu with him.
When the Conservatives denied the claim, an apparently furious Mr Rothschild - an Oxford friend of Mr Osborne - stoked the row by announcing he had an independent witness who could corroborate his story.
Mr Cameron continued to deflect criticism during a by-election campaigning visit to Glenrothes in Fife.
He said: "George Osborne has a perfectly clear record of all the discussions that took place. No money was asked for and none was received. You can't really have a financial scandal without any finance. That's all there really is to say about it."
