"We are very happy about their support," Art Basel Communications Manager Maike Cruse told ABC News Thursday.

At the event, which opened Thursday, patrons sipped champagne and gazed at the pricey artwork, including a Rene Magritte painting on sale for $11.5 million.

A grand jury indictment a month ago said UBS "solicited new business from existing and prospective United States clients at Art Basel Miami Beach," ABC News said.

The bank is accused of helping as many as 20,000 wealthy depositors hide money from the Internal Revenue Service.

"They smuggled assets out of the country to help those people conceal what they should have paid the IRS," said Jack Blum, a Washington tax lawyer.

"So the question is, why should a bank like that be allowed to continue in business?" he said.

At this year's show, "I'm here to talk about art, not about investigations, thank you very much," said James Price, co-head of the UBS Wealth Management Advisor Group.