WASHINGTON - A SENIOR executive at Swiss banking giant UBS has been charged with conspiring to defraud the United States of tax revenues, officials said on Wednesday.

Raoul Weil, chairman of the bank's global wealth management service in Zurich, was indicted by a grand jury in Fort Lauderdale, Florida, on Nov 6 for conspiring with other executives, private bankers and clients of the firm, the US Department of Justice and the Internal Revenue Service (IRS) said.

According to the indictment, between 2002 and 2007 Weil supervised the Swiss bank's overseas activities that serviced some 20,000 US customers.

The indictment alleges that by using encrypted laptops and other counter-surveillance techniques, Weil and his co-conspirators helped US customers conceal around US$20 billion(S$30.18 billion) in assets from the IRS.

Weil instructed fellow Swiss bankers to increase their cross-border activities knowing that such activity meant bankers would be violating US law.

'Every American who pays his or her taxes should be offended that a select few use anonymous offshore accounts to avoid paying their fair share,' said Mr Alexander Acosta, US Attorney for the Southern District of Florida.

'Professionals, including bankers, who promote fraudulent offshore tax schemes against the United States, will be held accountable,' said Mr John Marrella, Deputy Assistant Attorney General of the Justice Department's Tax Division.

UBS confirmed in a statement on Wednesday that Weil worked for the bank and was previously head of the UBS wealth management international department from 2002 to 2007.

It added that Weil had decided 'that in the interest of the firm and its clients, and in order to defend himself, he will relinquish his duties at this time pending resolution of this matter.'

UBS also confirmed that it has ceased providing 'cross-border private banking services to US-domiciled clients through its non-USD regulated units.'

And the bank vowed it would cooperate with the investigation in the United States.

On Tuesday UBS and Swiss authorities had denied reports that they had handed over to US authorities files on Americans suspected of tax evasion.

'The Swiss authorities have not handed over any information as of now, contrary to what has been said,' a spokesman for the Swiss finance ministry said.

Her comments came after The Washington Post reported on Monday that the Swiss had handed over information on around 70 US clients of UBS to the US Justice Department. -- AFP