The revelations show how inquiries by the US authorities that started with UBS in 2007 have mushroomed to a number of Swiss banks, although no additional banks have been named.

The newspaper said the latest information stems from indictments of a Zurich accountant allegedly specialising in forming sham offshore companies and foundations, and two former UBS bankers who left after the latter’s decision to close its US business in 2008.

The documents show that numerous other Swiss private banks, at least one Liechtenstein group, and possibly two Swiss cantonal banks, are alleged to have knowingly opened accounts for UBS clients after the latter terminated the business at US pressure from 2008, it said.

In July, it was reported that US authorities have indicted three Credit Suisse private bankers yesterday, one being a senior executive, on charges that they allegedly helped US citizens evade taxes. Federal prosecutors in Alexandria, Virginia, filed criminal charges against Markus Walder, the former head of North America offshore banking and a former senior Credit Suisse executive; Susanne Rüegg Meier, a former manager; and Andreas Bachmann, a former banker at a subsidiary of the bank. Also charged was Josef Dorig, the founder of a Swiss trust company that worked with the bank.

In 2009, UBS paid a $780 million fine to settle criminal charges that it had helped US citizens evade tax; in a separate, civil case, the bank has handed thousands of client account details to the US authorities as part of an agreement between the US and Switzerland. The move was seen as a historic breach of Switzerland’s bank secrecy rules.