U.S. authorities have widened their investigation to 17 Swiss banks under scrutiny for possibly helping wealthy Americans dodge taxes, a Swiss newspaper reported, citing several financial sector sources.

Strict secrecy has helped Switzerland build up a $2 trillion offshore financial sector, and in recent years the country has faced an international campaign against tax evasion as cash-strapped governments seek to boost revenue.

Credit Suisse is the formal target of an investigation in the United States and Julius Baer is also being probed. UBS, Switzerland's biggest bank, has already paid a big fine and was forced to reveal the names of some 4000 clients to U.S. authorities.

The German-language Handelszeitung said in a preview of its Thursday edition that 17 banks were under scrutiny, up from the previous figure of 11.

The Handelszeitung gave no further details.

For more information go to: http://www.reuters.com/article/2011/10/26/us-swiss-tax-investigation-idUSTRE79P6II20111026