Labour’s attempts to impose new curbs on party funding have been dealt a blow after an analysis by The Times showed that trade unions donated twice as much to local parties before the last election as the wealthy Tory businessman, Lord Ashcroft, whom ministers have accused of trying to “buy” marginal seats.

The Government will signal tomorrow in the Queen’s Speech that it is considering changing the rules on party funding. Ministers argue that Lord Ashcroft, the Tory vice-chairman in charge of funding operations in the 100 most winnable seats, has created a financial “arms race” by pouring tens of thousands of pounds into constituencies.

But an analysis by The Times revealed that while Lord Ashcroft gave almost £850,000 during the last Parliament to Tory seats, unions collectively gave £1.58 million directly to constituencies. Other wealthy Tory businessmen gave a further £470,000, meaning the Tories’ marginal seats received £1.38 million, broadly comparable with the unions’ constituency donations.

Although union funding is given to a wider range of constituencies than the tightly organised Tory system, several marginal seats received significant amounts, such as Derby North, where unions donated £25,500, more than five times the amount given by Lord Ashcroft. The Conservatives say that Labour is wrong to suggest that money from Lord Ashcroft is distorting the political battleground, insisting that the marginal seats campaign “levels” an unfair existing system, and accuse Gordon Brown of “gerrymandering” the rules in his party’s favour.

In the speech tomorrow, the Government is expected to stop short of announcing detailed proposals for new rules after the all-party talks on funding reform collapsed six days ago over the future of the handling of trade union affiliation fees.

Gordon Brown is under pressure from Labour ministers and MPs to change the law to stop the Tories pouring thousands of pounds into seats between elections when there is no limit on spending.

An analysis of the Electoral Commission register by The Times suggests that while there was little evidence of a co-ordinated Labour “target seat” campaign during the last Parliament, their spending in some marginal seats was comparable with Lord Ashcroft’s.

In Derby North, number 15 on the Tory target list, the Communication and Workers’ Union gave £25,500 in 20 donations to the local Labour party, compared with £5,000 from Lord Ashcroft to the local Tory party. In Hastings and Rye, unions donated £16,465 to Labour, compared with £12,068 from Lord Ashcroft’s company, Bearwood Corporate Services, for the Tories. In Clwyd West, unions gave a total of £7,500, compared with a £10,000 donation by Lord Ashcroft’s organisation. Since the 2005 general election, trade unions and Lord Ashcroft have donated roughly similar totals, with the former making 48 donations to Labour seats, totalling £64,018, and the latter making 9 donations over the same period to Tory target seats, with a total of £72,970.

Chris Grayling, the Tory Shadow Cabinet member, said: “This is further evidence of rank hypocrisy on the part of Gordon Brown. He ensures that trade union money is sacrosanct but is quite prepared to gerrymander electoral law to stop other parties from campaigning in marginal seats and help his own self interest.”

Labour sources retort that Conservatives have spent 2.4 times as much as Labour in the 24 seats they won at the last election. They also argue that the registers only show donations, not spending, and that as the Tory target seat campaign is increasingly using funds from central coffers to pay for the marginal campaign, the registers do not reflect the true situation.

Under proposals by Sir Hayden Phillips, the former senior civil servant asked to broker a deal on party funding, donations and loans from individuals would be capped at £50,000 and a single spending limit would be imposed of £150 million per party for local and national campaigning for each Parliament, including £20 million for a general election. The talks broke down over the future of the handling of trade union affiliation fees.

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