The Labour Party, which is more than £17m in the red, has persuaded some of its major lenders to write off their loans but wealthy donors are still backing the Conservatives in far larger numbers and with more money.

Electoral Commission figures for the second quarter of 2008, published yesterday, show donations to the Tories have out-paced those to Labour by £1.8m.

Between April and June this year, the Conservatives received donations of £5.6m, mostly from wealthy individuals, compared with £3.8m for Labour, which came mainly from the trade union movement.

The data, which is released every three months, also showed Labour's total debt stands at £17.8m - unchanged since the party last declared its finances to the commission three months ago. This is made up of £13.6m in loans and £4.2m in credit facilities.

The Conservatives' total debt is somewhat healthier, with the party owing just over £12m, comprising £6.9m in loans and £5.1m in credit facilities.

The figure does not include donations from the public purse, known as Short money, which helped swell the Tory coffers by a further £1.3m to £6.9m.

Labour received £132,156 from public funds, taking their total donations to £3.9m. The Liberal Democrats received £945,192 in donations and £637,625 from public funds, taking their total donations in the period to £1.5m.

SNP donations were a modest £13,627, with £81,073 from public funds, giving them total donations of £94,700 for the quarter. The SNP owes just over £1m, with £426,343 in loans and £432,000 in credit facilities.

The data, from the commission's online register of donations and borrowing, shows Labour paid back £30,000 of borrowing during the period but made £66,000 of new borrowing. The Tories did not pay back any debt, but borrowed another £10,000.

In addition, Labour is reported to have persuaded two of its large lenders, Lord Sainsbury who loaned £2m and Sir Gulam Noon who lent £250,000, to convert their outstanding loans into donations.

The move is due to be reported to the Electoral Commission in the next quarter when the party hopes to be able to announce further improvements in its financial situation.

Of Labour's donations during the period, £871,000 came from four individuals, while the Unite union was the single biggest donor to the national party - giving just over £1.3m.

The Conservatives claimed the figures proved Labour was in the trade unions' pocket, but union donations are down slightly with the £2.5m donated in the second quarter of this year amounting to 66% of the total £3.8m. Unions provided a similar amount (£2.6m) in the first quarter of this year, but that represented 82% of the total £3.1m received by Labour.

Labour's big four private donors in the period were Sir Ronald Cohen (£250,000), the private equity millionaire who accompanied the Prime Minister on his recent visit to the Middle East; Nigel Doughty, founder of the private equity firm Doughty Hanson, and John Aisbitt, a former Goldman Sachs partner, who each gave £250,000, and Steve Lazarides, the art dealer for the street artist Banksy, who donated £121,600.

Other notables supporting the Labour Party included comedian Eddie Izzard, who donated nearly £10,000.

The Tories' biggest single donation was £250,000 from JJB Sports founder and Wigan Athletic FC owner David Whelan, and the biggest corporate donation was from IPGL, which donated £208,000, while William Cook Holdings donated £100,000.