A wealthy Florida yacht broker, caught up in a federal probe of UBS AG , pleaded guilty on Tuesday to using the Swiss bank to hide more than $3 million in assets from the U.S. government.

The guilty plea by Robert Moran, of Lighthouse Point, Florida, was thought to be the first by a UBS client in a widening tax-evasion investigation of the bank, a U.S. Justice Department official said.

Moran, who runs a Florida-based company called Moran Yacht and Ship that bills itself as one of the world's leading yacht merchants, entered his plea in federal court in Fort Lauderdale.

He faces a maximum of three years in prison and a $250,000 fine. Sentencing is set for June 26.

Moran admitted filing a false 2007 U.S. tax return and accepted responsibility for concealing more than $3 million in assets in a secret account at UBS in Switzerland, the Justice Department said.

According to court records, Moran was the beneficial owner of a UBS account in the name of Winter Drive Investments S.A., a nominee Panamanian corporation, the department said.

From 2001 through 2008, Moran communicated with bankers at UBS via email, telephone and in person about the purchase and sale of securities, and the conversion of investments from U.S. dollars to Euros, it added.

SLEEK, MULTIMILLION-DOLLAR YACHTS

The website of Fort Lauderdale-based Moran Yacht and Ship, which lists Moran as its president, gives the addresses of the company's business offices in Fort Lauderdale, Moscow and Antibes, France.

We are recognized as being the authority and most successful company in the world with regard to the sale and construction of quality built motor yachts, the site says.

Displaying photographs of sleek, multimillion-dollar motor yachts, it offers services to clients wishing to build, buy, sell or charter yachts, from 60 to 500 feet.

UBS, Switzerland's largest bank, in February acknowledged that it helped U.S. clients conceal assets from the U.S. government. It agreed to pay a $780 million fine and identify some of its American clients.

U.S. authorities earlier this month charged Florida-based accountant Steven Michael Rubinstein in the first of what they said could be a series of tax-evasion prosecutions of American UBS clients. A Fort Lauderdale judge last week ordered Rubinstein released on a $12 million bond pending an arraignment set for next Wednesday.

U.S. authorities have said there will be other tax evasion prosecutions against American clients of UBS as they wage a legal battle with the Swiss bank to try to force it to give up the names of tens of thousands of Americans suspected of cheating the U.S. government by concealing accounts abroad.

We will continue to prosecute those who use offshore schemes to avoid paying their taxes, Alexander Acosta, U.S. attorney for the Southern District of Florida, said in a statement on Tuesday.

(Reporting by Randall Mikkelsen and Tom Brown, Editing by Pascal Fletcher and Eric Beech)