The cash-for-access scandal engulfing David Cameron has inflicted deep damage on the Conservative Party's standing, according to a ComRes survey for The Independent.

The polling gives Labour a 10-point lead over the Tories, the highest in a ComRes survey for seven years. But, significantly, in interviews conducted since the affair emerged on Sunday, Labour was a remarkable 17 points ahead.

In the 337 interviews conducted on Saturday, before the cash-for-access revelations, Labour enjoyed a lead of only four points. Labour was on 39 per cent, the Tories on 35 per cent and the Liberal Democrats on 11 per cent. But in the 350 interviews that took place on Sunday and yesterday, after the disclosures, Labour was 17 points ahead. Labour was on 47 per cent, the Tories on 30 per cent and the Liberal Democrats on 11 per cent.

The survey also found two out of three people regard the Tories as "the party of the rich" as a result of last week's Budget, which cut the 50p top rate of tax on incomes over £150,000 a year while imposing a "granny tax" on pensioners.

Tory modernisers fear Mr Cameron's drive to "detoxify" his party could be undermined by the combination of the Budget and the revelation that the Tories' treasurer Peter Cruddas offered potential donors dinner in the Prime Minister's Downing Street apartment if they gave £250,000 to the party.

Mr Cameron tried to draw a line under the affair by publishing a list of Tory donors he entertained at both No 10 and Chequers, his official country residence. But he was criticised for refusing to make a Commons statement on the affair or take questions from journalists on it.

Labour will today keep up the pressure on the Prime Minister by challenging him over Mr Cruddas's suggestion to undercover reporters from The Sunday Times that the Tories might be able to find a way round the law banning foreign donations. It also emerged that:

* One of Mr Cameron's private dinner guests runs an oil trading company that stands to make millions from the new British-backed government in Libya. He had given £50,000 to the party.

* Another invitee gave an interview in which he said he "had it first-hand" from "very senior" members of the Government that Mr Cameron would oppose a European financial transaction tax.

* Sir Christopher Kelly, chairman of the anti-sleaze watchdog, rejected as "much too high" Mr Cameron's proposal to bring in a £50,000 cap on individual donations to political parties.

* The Conservatives paid for some functions at Chequers attended by donors, leaving the party open to criticism this was a reward for giving money to it.

On a torrid day for the Conservatives, Downing Street was forced to release a list of 12 major donors who were invited with their partners to four dinners in Mr Cameron's flat. Between them the guests had given or lent the party almost £18m since Mr Cameron became leader. A second list of five donors invited for lunches at Chequers was released later.

According to the lists, those entertained at Downing Street included Michael Spencer, head of the biggest broker of financial transactions in London, who was invited to Mr Cameron's flat for dinner last month. Mr Spencer has given more than £3m to the Conservatives through his company and £200,000 personally.

A few weeks earlier he gave an interview to a financial magazine in which he said he had it on first-hand authority that Mr Cameron would veto a financial transaction tax.

The other invitees included:l Ian Taylor, head of oil trading firm Vitol, who played a vital role in helping Libyan rebels by supplying them with petrol for their vehicles.

* JCB chairman Sir Anthony Bamford, who has donated £70,000 to the Tories since Mr Cameron became leader while his company has given almost £1.7m.

* The financier Michael Farmer, who has given around £2.5m and tycoon Michael Hintze, who gave more than £1.2m.

In remarks before making a speech on dementia, Mr Cameron confirmed that in future the Conservatives would publish a register of major donors.

The Government dispatched Francis Maude, the Cabinet Office minister, to make a statement in the Commons to shield Mr Cameron from Labour demands he address MPs.

Amid rowdy scenes, Ed Miliband accused Mr Cameron of showing "utter contempt" for the Commons by failing to attend. "I think we all know why," the Labour leader said. "He has got something to hide." He called for an inquiry.

Mr Maude was almost drowned out by Labour shouts of "Where's Cameron?" He said Conservatives were ready to accept a cap on donations, but only if it applied not only to individuals and companies but to trade unions too – which Labour has resisted.