Jun. 26--In the latest display of the United States government's concerted assault on Swiss banking secrecy, a wealthy Boca Raton accountant who hid money at Swiss banking giant UBS pleaded guilty Thursday to filing a false tax return.

Steven Michael Rubinstein, an accountant for a Coral Springs yacht company, is the first U.S. citizen to face criminal charges stemming from UBS records obtained by the federal government as part of a groundbreaking deferred prosecution agreement with the Zurich-based bank.

Rubinstein admitted to the felony charge in federal court in Miami. According to court papers, he hid money in a UBS Swiss account under the name of Hybridge International Ltd., a sham company in the British Virgin Islands, and failed to pay income taxes on it.

Mark Arena, a spokesman for UBS -- the main sponsor for Art Basel Miami Beach -- declined to comment on the case against Rubinstein, who was one of 250 to 300 UBS customers whose account details were turned over to the United States as part of the agreement.

As the Obama administration steps up pressure on offshore tax evaders, the case serves as a shot across the bow for thousands of others who hold secret offshore bank accounts.

"More prosecutions are expected to follow, as we continue to hold accountable those who conceal money and assets in an effort to avoid their income tax obligations," Jeffrey H. Sloman, the acting U.S. attorney for Miami, said in a statement.

Many people with secret offshore accounts at UBS and elsewhere have been rushing to make voluntary disclosures to the IRS and paying back taxes, interest and civil fines to deflect criminal charges, tax experts say.

"Word has gotten out from the publicity surrounding the UBS case and people are coming forward," said Alan L. Weisberg, a tax attorney with the Miami firm of Weisberg and Kainen, which represents clients from UBS and other banks in making voluntary disclosures to the IRS. "The government has the carrot and the stick."

According to court records, Rubinstein met with UBS bankers to discuss his Swiss account at the swank Art Basel Miami Beach, at various South Florida restaurants, and at his Boca Raton home, which prosecutors said was built and paid for with funds he repatriated from his offshore UBS account.

That entailed transferring more than $3 million from his UBS account to a bank account at HSBC in Monaco and then to a bank account in the name of Duroc Ventures Ltd. at HSBC bank in New York, the government said.