HMRC has already started criminal and serious fraud probes into more than 500 individuals and organisations, it said on Thursday, and will shortly start contacting the rest.

"They will be offered a window of opportunity to contact HMRC and disclose all their tax liabilities," the body said, adding that those that did not come forward will be investigated and could incur penalties of up to 200 percent.

HMRC said it was "acting on information received last year under a tax treaty."

A source at the tax authority said the information was obtained through an information exchange agreement with French authorities.

However, the original source of the data is a haul of up to 24,000 Swiss client accounts stolen from HSBC by a former IT employee, the source said.

The details subsequently found their way into the hands of tax authorities around Europe, including the UK.

Switzerland's coveted banking secrecy has come under increasing pressure as tax authorities in the United States, neighbouring European countries and now Britain step up crackdowns on hiding funds abroad.

The source at the HMRC said the probe was limited to the individuals, companies and trusts holding accounts and did not extend to an investigation of the bank itself.

A spokesperson at HSBC said: "HSBC does not condone tax evasion, and clients are responsible for their own tax affairs."

Earlier this year, the British government made 917 million pounds in new funds available to help fund the pursuit of tax evaders.

HMRC's Permanent Secretary for Tax Dave Hartnett said in a statement the latest move did not constitute a tax amnesty.

"There are no special rates of penalty or interest for those who come forward voluntarily. This is an opportunity for those who have made errors in the past to correct them," he said.

In August Switzerland and the UK struck a deal to tax money kept by British residents in Swiss accounts that could net around 5 billion pounds.