The Tories say they acted swiftly to declare the donations.

The Witney Conservative Party has voluntarily forfeited the cash to the Electoral Commission because the benefactors were not British voters.

Labour said it was "shocking", after Mr Cameron's criticism of Labour for its unlawful donations from David Abrahams.

But Tory aides said the incident was a "genuine mistake".

They say Mr Cameron had made it clear all along that errors would always occur at a local level.

Declarations

According to the Electoral Commission website, the two donations received by the Witney association on 21 August were subsequently found to have been impermissible.

The donors were Roger Fletcher, who gave £5,900 and Geoffrey Dobbs, who offered up an auction prize of £1,500.

It beggars belief that David Cameron was lecturing others and questioning their integrity, when he has not even bothered to check that his own house is in order John Mann Labour MP

Some £7,400 was handed over to the Electoral Commission on 16 November.

A Tory spokesman said: "As soon as we became aware that these two donations were not permissible we declared and voluntarily forfeited them to the Electoral Commission."

Labour MP John Mann, who wrote to the Electoral Commission to complain about the donations, said: "This is a shocking revelation.

"It beggars belief that David Cameron was lecturing others and questioning their integrity, when he has not even bothered to check that his own house is in order."

The disclosure comes after weeks of controversy over Mr Abrahams' donation to Labour of more than £650,000 under other people's names.

Under the Political Parties, Elections and Referendum Act 2000, details of any donor making gifts through a third party must be registered and reported to the Electoral Commission. Prime Minister Gordon Brown has said he knew nothing about the third-party arrangements.