Swiss bank UBS on Thursday announced at a US Senate hearing, that it will end offshore services for US residents and close 19,000 accounts with funds of $18 billion held by American tax evaders.

A six month-long US Senate Permanent Subcommittee on Investigations probe has examined LGT Bank in Liechtenstein, owned by the Alpine tax haven's royal family  and UBS, Switzerland's biggest bank, to expose how tax haven banks are assisting US taxpayers to evade taxes, in particular by urging US clients to open accounts in their offshore jurisdictions.

The Subcommittee said that UBS alone has an estimated 19,000 accounts in Switzerland for US resident clients with assets valued at$18 billion.

UBS representative Mark Branson, Chief Financial Officer of Global Wealth Management & Business Banking, testified at a Subcommittee hearing on Thursday titled "Tax Haven Banks and US Tax Compliance".

UBS is taking the actions necessary to address any compliance failures that may have occurred in the US cross-border business, says the statement delivered by Mark Branson on behalf of UBS, explaining that the bank has decided to exit entirely the business in question. "That means UBS will no longer provide offshore banking and securities services to US residents through its bank branches. Such services will only be provided to residents of this country through companies licensed in the United States", Branson told the Subcommittee.

Second, UBS is working with the US Government to identify the names of US clients who may have engaged in tax fraud. Client identity is generally protected from disclosure under Swiss law. But such privacy protections do not apply when disclosure of client names is requested in connection with an investigation of tax fraud and where the requests are presented to the Swiss government through established legal channels. UBS will fully support and assist that process.

At the hearing, Branson also pointed out that the cross-border business under the QI Agreement was – and is – entirely legal in both Switzerland and the United States. Indeed, the QI expressly contemplated that US citizens could access bank accounts in Switzerland and other countries without providing a form W-9, as long as they held no US securities. Branson: "Unless or until those rules are changed, that is the framework with which we and other banks must comply."

Last year, in order to respond to the ongoing investigations of the US Department of Justice and the SEC, UBS said it launched a comprehensive internal investigation into its cross-border business with US customers. Branson:

"We did have detailed written policies that prohibited our employees from engaging in some of the conduct that our internal investigation has uncovered, such as assisting in the creation of sham offshore companies to defraud tax authorities. While our own review is not complete, it is apparent now, that our controls and supervision were inadequate. UBS is committed to taking both corrective and disciplinary measures."

The Permanent Subcommittee on Investigations Chairman was surprised by the UBS decision.