The principality’s authorities informed the bank, also known as LLB, and its American clients that certain account details have been requested by the US.

The group request covers accounts with at least $500,000 at any time since the beginning of 2004, according to a letter sent to a bank client from the Liechtenstein tax authorities and dated 30 May, Bloomberg reported. Liechtenstein amended a tax law in March to enable the group request, according to that report. 

The bank did not give any further details, other than confirming it had received the data request, when contacted by this publication. The US Internal Revenue Service declined to comment.

The US is carrying out a criminal probe into 11 Swiss and non-Swiss banks suspected of selling offshore tax evasion services to tens of thousands of wealthy US citizens. Inquiries, growing out of scrutiny of UBS, are focused on Credit Suisse and Basler Kantonalbank among others.

As part of the probe, a US district court indicted Wegelin and Co, a 270-year-old Swiss private bank, in February for allegedly conspiring with US taxpayers to hide more than $1.2 billion from the Internal Revenue Service. It was the first time an overseas bank had been charged by the US for facilitating tax fraud by taxpayers, a statement from the Department of Justice said at the time. Alongside the criminal charges, the US government seized around $16.2 million on deposit at UBS held in the name of Wegelin & Co.

Wegelin, which claims to be the oldest Swiss bank, was sold to Raiffeisen in January as a consequence of the situation with the US authorities.