The U.S. Attorney's Office said Steven Michael Rubinstein, 55, of Boca Raton appeared in U.S. District Court in Fort Lauderdale on charges of filing a false tax return. He was ordered held until a hearing next week.

The Obama administration wants UBS to turn over information on thousands of U.S. customers who concealed their accounts from the government in violation of tax laws. UBS has formally accepted responsibility for helping Americans hide assets and agreed to pay $780 million in fines and restitution.

Last month, tax lawyers told The Associated Press that demands for information and evidence have increased sharply since the government sued UBS AG to try to get the names of tens of thousands of U.S. citizens who may have dodged taxes by hiding accounts. Swiss authorities have said they will fight to protect their tradition of bank secrecy.

In federal court papers, special agents with the Internal Revenue Service said that Rubinstein deposited more than $2 million in Kruggerrand gold coins into his UBS accounts and bought securities worth more than 4.5 million Swiss Francs through the accounts. Authorities also said he met with UBS bankers in several locations around South Florida from 2001 through 2008, including a meeting at Art Basel Miami, a tony international art fair whose main sponsor is UBS.

Rubinstein's Miami attorney, Robert Panoff, did not return calls for comment Thursday afternoon.

This isn't the first case involving UBS to land in Florida courts. In January, authorities charged Raoul Weil — a senior executive with UBS — with conspiring to hide $20 billion in assets from the IRS using secret overseas accounts for thousands of wealthy customers. Weil's attorney said in February that his client is innocent and is a victim of a political dispute between the United States and Switzerland over Swiss bank secrecy.

And a former UBS banker, Bradley Birkenfeld, pleaded guilty last year in Fort Lauderdale to fraud conspiracy charges and has been cooperating extensively with U.S. investigators. Birkenfeld has not yet been sentenced.

The IRS has been increasing pressure on Americans who kept the counts to come forward, saying last week that they had six months to come clean and turn over any evidence against their advisers or bankers.

"Combating offshore tax evasion has been and will continue to be one of the IRS's top priorities," said IRS Commissioner Doug Shulman, in a statement. "Today's actions show the IRS is committed to pursuing people hiding income offshore. Anyone in this situation needs to immediately come in through our voluntary disclosure process before it's too late."