Meanwhile, the Australian newspaper said that Australians with political connections are among those clients of LGT, the bank controlled by the Liechtenstein royal family, who secretly received $18 billion from tax havens last year, tax officials claim.

In the UK case, some clients have been contacted by HM Revenue & Customs, the UK tax authority, which says it will consider prosecuting those who have lied about their assets in other probes. Inquiries are expected to take two or three years.

Separately, the next phase of HMRC’s investigation into offshore account holders is set to be launched over the next few months, along similar lines to last year’s disclosures by UK banks. It is seeking legal notices requiring an initial batch of about 25 foreign banks to reveal information about clients with offshore accounts.

Since the Liechtenstein tax evasion scandal broke in February this year, investigators have received more information from the former employee of LGT who sold internal bank details to German and other tax authorities.

The revelations were examined in a US Senate subcommittee report last week. This concluded that the “murky operations” of banks such as LGT helped US taxpayers evade an estimated $100 billion of taxes each year.

Investigators have focused on more than 15,000 LGT clients with total funds of £100 billion-£110 billion invested through 4,000 foundations and other entities designed to provide anonymity. About 50 countries believe their citizens have undisclosed assets in LGT, headed by Germany, which has details of roughly 1,400 foundations.

In the US, the Internal Revenue Service has identified at least 100 US citizens who hid money in Liechtenstein.  The Alpine state's 15 other banks are coming under pressure to co-operate with foreign tax authorities.

Meanwhile, in the Australian case, the Australian Taxation Office told the US Senate inquiry that it has met difficulties applying Australian tax law to structures such as Liechtenstein foundations.

Australia's second-richest man, Frank Lowy, and his three sons have been named in a report relating to the use of Liechtenstein-based bank LGT Group. It was alleged that a structure called the Luperla Foundation was set up for the Lowys to hide up to $100 million in assets from the tax office.

The Lowys deny the allegations. They are one of 20 Australian groups of people being audited by the tax office over the use of Liechtenstein bank accounts.