New subsidiary Vontobel Swiss Wealth Advisors, which will be based in Zurich, will serve US clients with declared assets and will be regulated by the US Securities and Exchange Commission (SEC), Vontobel said in a statement.

“Increasing numbers of American private clients are seeking investment opportunities outside the US. However, US wealth and asset managers cannot - or can only partly - meet the growing demand for investments in European and Asian equities or foreign currencies. As a result, these clients are now looking for reliable financial partners with a good international track record in this field,” the bank said.

“Vontobel Swiss Wealth Advisors AG will focus on providing wealth and asset management services that are specially tailored to US requirements. Its offering will be targeted at American private clients with declared assets as well as external asset managers with a corresponding client base,” the statement continued.

The development highlights how Switzerland’s banking industry, which accounts for about 12 per cent of the Alpine state’s gross domestic product, is having to act to cope with a world in which Switzerland’s bank secrecy laws are seen as increasingly under threat.

Already, banks including UBS, Julius Baer and Wegelin have ceased to provide offshore banking to US citizens. UBS, in a high-profile case, is to pass over some client account details to US authorities under a deal between the Swiss and US governments. The agreement has been held up by a ruling from a Swiss court but the transfer is now expected to proceed after lawmakers recently voted on a law governing the transfer of the UBS data.

Vontobel said the changing legal and tax landscape meant that its new service made strategic sense.

"The situation facing US clients has altered significantly during recent months as a result of more stringent US tax legislation. As an internationally active wealth and asset manager, we believe it is our duty to offer our clients appropriate solutions that take account of these changes. We have therefore developed a viable long-term solution for US citizens living in or outside the US, as well as for non-US citizens residing in the US, that is compliant with regulatory requirements," said Peter Fanconi, Head of Private Banking at the Vontobel Group.

Vontobel has opened new branches in Berne and Basel earlier this year.