The Conservatives will today seek to stoke up pressure on Labour over donations by forcing a debate in the Commons chamber on party funding.

David Cameron last night switched the subject for this afternoon’s regular “Opposition Day” debate in the Commons to political fund-raising, as Peter Hain became the latest Cabinet minister to admit irregularities over donations. The Work and Pensions Secretary apologised after revealing that gifts to his unsuccessful campaign for Labour’s deputy leadership earlier this year were not properly registered.

Mr Hain - who had already admitted failing to register a £5,000 donation from Jon Mendelsohn, Labour’s chief fundraiser - said that he had informed the Electoral Commission and was reviewing all donations to his campaign.

He will today come under further pressure to reveal exactly who provided the money to fund his campaign, and why he did not supply the Commission with full details when he was required to do so.

His surprise admission came as Gordon Brown tried to regain control of the issue by pressing forward with wholesale reforms to the system for financing political parties.

Addressing MPs and peers at a meeting of the Parliamentary Labour Party in Westminster last night, the Prime Minister said that he was as angry as any of them about the row over donations sparked by last week’s revelation that thje property developer David Abrahams had given more than £650,000 to Labour through middlemen. Mr Brown said that it was crucial to deal with problems over party funding once and for all.

A poll for BBC2’s Newsnight last night suggested that 57 per cent of voters now view Mr Brown as “tainted by sleaze” - almost exactly twice the 28 per cent who said the same of Mr Cameron.

But Mr Brown told the packed PLP meeting that rows over fund-raising would not wreck Labour’s chances at the next General Election, saying: “At the end of the day, it is not money that decides elections, it is ideas.”

It is understood that Mr Brown is now ready to accept that unions should be covered by a proposed £50,000 cap on donations from individuals and organisations.

Labour hopes to make up any loss in income from union gifts by increasing the amounts coming in from the political levy paid by individual union members through their subs. A more “transparent” affiliation scheme would allow union members to opt out of the political levy but is thought likely to lead to an increase in the numbers recorded as being affiliated to Labour.

Any reform package is also likely to include a limit on campaign spending covering an entire Parliament, which would address Labour concerns over Tory donors like Lord Ashcroft pouring millions into marginal seats outside election periods.

But Mr Brown said that he was not proposing further public funding for political parties “at this stage”. The Prime Minister said new laws would be produced “quickly” and called for all-party support.

Mr Cameron, who last month pulled the Tories out of cross-party talks on funding, yesterday indicated he would back fresh moves to secure agreement on the issue provided Labour did not “bury its head in the sand” and seek to exclude trades unions from any cap on single donations.

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