WASHINGTON (AFP) - US authorities Thursday said they have charged a Florida man with hiding income and assets in a secret account with Swiss banking giant UBS, the first prosecution in the massive tax fraud probe.

Steven Michael Rubinstein, of Boca Raton, has been criminally charged with filing a false income tax return, the Justice Department and Internal Revenue Service (IRS) said in a statement.

UBS admitted guilt to US tax fraud in February and identified some 300 US clients, including Rubinstein, who are suspected of tax fraud by US authorities.

The bank was forced by the Swiss financial regulator to hand over details on the suspects, raising an outcry in Switzerland where banks operate under strict financial privacy laws.

UBS also paid a fine of US$780 million as part of a provisional deal to settle the US tax fraud charges.

US officials in a subsequent lawsuit against UBS have requested details on 52,000 more UBS clients suspected of tax fraud.

But UBS, the world's largest manager of private wealth, has refused to hand over the information.

"On February 19, 2009, we reached an agreement with UBS that included, for the first time, the disclosure of the identities of taxpayers that were illegally using Swiss bank accounts to evade US taxes," said R. Alexander Acosta, a federal attorney for the southern district of Florida.

"Today is the first of the prosecutions resulting from that disclosure, but it will not be the last."

Rubinstein appeared in a Florida court Thursday and was temporarily detained pending a bond hearing next Tuesday, officials said.

According to court records, they said, Rubinstein is a chartered accountant who works for an international company that assists clients to build, buy and sell yachts.

Rubinstein allegedly filed a US tax form for tax year 2007 that failed to report that he had an interest in, or signature authority over, a financial account at UBS in Switzerland.

He also was accused of failing to report the income he earned on any UBS Swiss bank accounts.

Court records showed that Rubinstein was the beneficial owner of UBS accounts in the name of Hybridge International Ltd., a British Virgin Island corporation through which he allegedly shuffled millions of dollars in and out of the accounts in a bid to hide them from US tax authorities.

"Combating offshore tax evasion has been and will continue to be one of the IRS's top priorities," said IRS commissioner Doug Shulman.