The system allows the party to trouser the cash without naming the wealthy backers it comes from.
Anyone who gives more than £1,500 a year to a political party should be named on an Electoral Commission website.
But if the money is funnelled through a club, donors can give up to £7,500 and remain anonymous.
However, the names are known to the Tories and opponents claim donors are buying access and influence at the highest level without public scrutiny.
Since David Cameron became leader in 2005 the party has received more than £1million from the supper clubs, according to searchthemoney.com.
It has gone to three Cabinet ministers and several MPs in marginal seats.
The United and Cecil Club has given more than £392,000, while the Carlton Club has give £549,000.
Education Secretary Michael Gove’s local party got £67,000 from the Magna Carta Club and £39,000 from the Strangers Gallery.
Critics say the system, though legal, makes a mockery of the PM’s pledge in 2010 to clean up politics.
Earlier this year he was to name rich backers he wined and dined at Downing Street.
The Unite union’s general secretary Len McCluskey said: “Those in charge of the rules for funding political parties takes a much closer look at how these secretive Tory supper clubs are being run.”
A Tory spokesman said: “All donations to the party are properly declared.”
Dinner party greasy-polers loomed large in the list of donors highlighted in official figures published yesterday which also showing that donations to political parties fell by almost £1 million during the second quarter of 2012.
The Electoral Commission said that £7,873,478 in funding had been reported – down £992,312 on the first three months of the year.
The Tories received £3,785,579, Labour raked in £2,964,471 and the Lib Dems were handed £717,797.
The biggest donor to the Conservatives was financier Michael Farmer, who was named as one of the cash-for-access private dinner party guests hosted by Prime Minister David Cameron at No 10.
Mr Farmer, who was appointed the Conservatives’ co-treasurer in February, gave the party £512,450.
The Liberal Democrats’ largest donation was £250,000 from Brompton Capital Limited, a property development company owned by entrepreneur Rumi Verjee.
He qualified as a barrister before launching the first British franchise of Domino’s Pizza in the 1980s and last year dined with party leader Nick Clegg at his grace-and-favour residence Chevening, in Kent.
Labour received £840,275 from Unite, the largest donation made in the period by a single source, as well as £429,558 from Usdaw and £313,863 from GMB.
After the three main parties, the Green Party received the most donations with £180,060, followed by the British National Party with £100,000.
Plaid Cymru received £17,500 and the Scottish National Party got £2,500.
In 2010 donations to political parties reached their highest level on record around this year’s general election, the Electoral Commission has said.
Some Â£26.3 million worth of gifts were reported by 16 parties as having been received in April, May and June, the commission said.
The main beneficiaries were the Conservative Party, which got Â£12.3m, Labour with Â£10.9m and the Liberal Democrats with Â£2m.
The three main parties also took a share of more than Â£1m of public funds and owed more than Â£31m between them at the end of the period.
Labour had the highest borrowing at the end of June, with Â£16,645,172, followed by the Tories on Â£13,128,326 and the Lib Dems on Â£1,600,314.
Electoral Commission chief executive Peter Wardle said: “Voters have come to expect a high level of transparency about the way political parties are funded and never more so than for the period covering a general election in the UK. Voters will want to see who funded political parties during the election campaign and contributed towards this record-breaking quarter.”