David Cameron has intensified the pressure on Gordon Brown, saying it "beggars belief" the Prime Minister did not know of David Abrahams' donations by proxy to the Labour Party.
The Conservative leader renewed his attack on Mr Brown, amid claims that more people knew of Mr Abraham's donations through third parties than previously thought.
Yesterday, the property developer used an article in the Independent on Sunday to insist that "party officials" knew of his wish to remain private and "were only too happy to accept my money through intermediaries".
He said: "Only a very few officials and party figures in higher echelons of the national party were aware" and said he was "received warmly at functions and was occasionally contacted to make further donations".
A spokesman for Mr Abrahams denied that he had suggested that up to 10 people in the Labour party knew of his donations via third parties but said the businessman would co-operate with inquiries into the donations.
Mr Cameron increased the pressure on Mr Brown, saying he found it "frankly incredible" that former Labour general secretary Peter Watt and Labour fundraising chief Jon Mendelsohn were "professing complete ignorance of one of the most basic bits of the law which is, the money's got to come from the person who says they gave it to you. And it's as simple as that."
He said: "I think the problem for the Prime Minister is, he appointed Mr Mendelsohn to raise money for him before the election. And are we really meant to believe that Mr Mendelsohn didn't know what the law was, didn't tell anyone about it. Brown knew nothing? It just beggars belief."
Further trouble for Labour emerged yesterday as a Scottish National Party worker announced he had lodged a complaint about a 950 donation that was made to Scottish Labour leader Wendy Alexander from a Jersey-based businessman.
Please Keep Labour also faced claims that Mahmoud Khayami, another major donor who has handed over 830,000 to the party in the past eight months, was only added to the electoral roll a day before making his first party donation.Reuse content