Brown allies try to pin blame for scandal on the legacy of Blair

Allies of Gordon Brown sought to blame Tony Blair for Labour's secret donations as the Prime Minister urged the police to carry out "the fullest possible investigation" into the scandal.

Mr Brown wrote to Scotland Yard yesterday promising full co-operation with its inquiries. He said: "What happened in relation to these donations was unacceptable and it is in the public interest that any question of impropriety is answered."

In a sign that he is preparing to be interviewed by the police, the Prime Minister added: "I stand ready to assist your inquiry in any other way I can." He said he had asked Labour staff, MPs and peers to co-operate fully with the investigation, and to be "proactive" in providing information to the police without giving a "running commentary" in the media.

The Prime Minister will try to fight back today when he addresses Labour's national policy forum in London. But he will face questions about the funding crisis at an emergency meeting of the party's national executive committee.

His letter to Scotland Yard reflects his determination to sweep Labour's stables clean to try to limit the damage from the controversy. It will be seen as a deliberate contrast with Mr Blair's response to the "cash for honours" investigation, when the police complained of obstructive tactics by Downing Street.

The saga took a fresh twist last night as David Abrahams claimed he had discussed his donations by proxy with Labour's fundraiser Jon Mendelsohn as early as April.

Mr Mendelsohn, who started work as Labour's head of general election resources in September, has said he was told of the donations after he took up the job and last night issued a statement flatly denying discussing the matter with Mr Abrahams.

Mr Abrahams said in a statement: "I always discussed the manner of my donations with the appropriate party officials and it was never suggested to me that I was doing anything wrong. I am not going to discuss particular meetings with particular individuals, save to confirm that Jon Mendelsohn discussed this method of donating money with me in April."

Mr Mendelsohn said: "This is completely untrue. I met Mr Abrahams at a charity dinner in April before I began working for the Labour Party. I did not discuss with him donations to the Labour Party, and did not discuss donating through third parties. I look forward to co-operating fully with the police investigation into these matters."

Also last night, Mr Abrahams said the donor affair was "a product of cock up, not conspiracy".

Earlier, the Metropolitan Police said its inquiry, called "Operation Minera", would investigate "potential breaches" of the Political Parties, Elections and Referendums Act 2000.

As the Electoral Commission presented its file on the affair to the police, there were growing signs that Brown allies will argue that the crisis stems from failings at Labour HQ that he inherited when he became party leader in June.

Jack Straw, the Justice Secretary, said: "It's absolutely true that this seems to go back for about four years, and frankly one of the reasons why all of us are irritated to distraction by what's happened is that we assumed that these historic problems had been sorted out with all the additional controls that were put in place following the so-called 'cash for honours' issue."

Labour MPs are also dismayed that the fallout from the 600,000 donated to the party by Mr Abrahams through four intermediaries has led to a public dispute between Mr Brown and Harriet Harman, the party's deputy leader. Several MPs have protested to Ms Harman's office about what was seen as an attempt to draw Mr Brown deeper into the controversy. On Thursday, the Harman campaign team in Labour's deputy leadership election revealed that it accepted 5,000 from Janet Kidd, one of Mr Abrahams' proxy donors, after being given her name by Chris Leslie, who was Mr Brown's leadership campaign manager.

Yesterday Ms Harman denied that she had implicated Mr Brown. "I strongly maintain that I have complied with the letter and the spirit of the law and I absolutely think that Gordon Brown has done the same," she said.

Wendy Alexander, the Scottish Labour leader, was forced to apologise after it emerged that she personally wrote to thank a Jersey-based businessman who contributed 950 to her leadership campaign despite being barred from donating because he is not on the British electoral register. Paul Green also disclosed that he had given a separate 950 donation to the party at this year's Scottish elections.

The trail from Abrahams to Harman

* Late May 2007: David Abrahams telephones Chris Leslie, Gordon Brown's campaign co-ordinator. Mr Abrahams suggests Janet Kidd as a possible donor. Mr Leslie contacts Mrs Kidd who "unprompted" sends a cheque for 5,000. After it emerges that Mrs Kidd was not personally known to members of Mr Brown's campaign team, Mr Leslie tears up her cheque.

* 24 June: Gordon Brown becomes Prime Minister. Harriet Harman becomes Labour deputy leader.

After the result Ms Harman's campaign team approaches Mr Leslie to find possible donors. Mr Leslie suggests Mrs Kidd and Ms Harman's team get in touch.

* 17 July: Janet Kidd donates 5,000 to Harriet Harman's deputy leadership campaign.

* 25 November: Reports emerge that Mr Abrahams has donated hundreds of thousands of pounds to Labour through middlemen. Peter Watt, general secretary of the Labour party, resigns the next day.

* 27 November: Ms Harman says she accepted 5,000 from Janet Kidd, but insists she did not know of the connection to Mr Abrahams.

* 29 November: Aides to Harriet Harman reveal that Mr Leslie passed on Mrs Kidd's details as a potential donor. Mr Leslie issues a statement outlining his role in the affair.