Zavieh, a San Francisco resident, conspired with five bankers, charged a grand jury in Fort Lauderdale, Florida, according to media reports. They included former UBS bankers Renzo Gadola, who was sentenced to five years probation last month, and Martin Lack, who was indicted in August and is considered a fugitive.

Zavieh opened an undeclared account with UBS in 1989 and transferred it in 2008 to a smaller Swiss cantonal bank after Gadola said his records could be disclosed to the IRS, according to the indictment, reports said.

"At some point if they come after me, I will fight it tooth and nail," Zavieh said in a June 2010 e-mail to Gadola, according to the indictment. "What is also interesting or perhaps appalling is that the laws of a country and perhaps its tradition is being broken to save a bank's ass for selling out its own clients who have been trusting and feeding them for years!"

Zavieh, a naturalized US citizen from Iran, is among dozens of taxpayers charged in a US crackdown on offshore tax evasion. According to Bloomberg, 21 bankers, lawyers and advisors have been charged; in Lack’s case, he was executive director of the UBS North America International business until 2003, when he set up an asset management company in Zurich.

UBS, like many of its Swiss peers, no longer provides offshore banking services to US citizens.