German authorities investigating tax evasion by Germans using banks in Liechtenstein have received a new offer of confidential information on accounts held there, officials said yesterday.

The finance ministry did not disclose who was behind the offer, the latest twist in a tax dodge probe that started in Germany but has spread around the world.

The affair began when, according to media reports, Germany's foreign intelligence service paid around €4.2 million for information on the accounts of Germans who parked their money in the Alpine principality of Liechtenstein in order to evade tax.

German broadcaster ARD said the latest offer came from a man who had previously blackmailed the Liechtensteinische Landesbank (LLB). The information was on a DVD containing details of over 2,000 client accounts worth more than €4 billion, it said.

A spokesman for LLB declined to comment.

State prosecutors in the northern city of Rostock said the data related to LLB but did not confirm the figures cited.

Senior public prosecutor Peter Lueckemann said he believed those offering the information were lawyers for a man involved in a Rostock blackmail case who was currently in prison.

The finance ministry said it had referred those behind the offer to the authorities conducting the tax investigation.

The probe has already led to the resignation of the chief executive officer of mail group Deutsche Post, and threatens to ensnare other rich, high-profile Germans.

International pressure has intensified on Liechtenstein to lift the cloak of secrecy from its banks. Liechtenstein has defended its secrecy rules and says it is cooperating with other countries.

Separately, Switzerland's biggest industry group protested against Germany's clampdown in a letter to German Finance Minister Peer Steinbrueck which was published in newspapers.

"You are openly urging bank employees to break the law and pass on private data. Such statements do not fit in our picture of a joint judiciary system," the group, Economiesuisse, said.

Mr Steinbrueck has vowed to wage a battle against all tax havens in Europe, naming Switzerland, Luxembourg and Austria as well as Liechtenstein. Austrian business leaders have also protested against the German moves.