Senators have called on the US justice department to force the Swiss banking group Credit Suisse to hand over the names of thousands of US citizens who used its accounts to evade taxes.
At a heated hearing of the permanent subcommittee on investigations on Wednesday the Democratic senator Carl Levin blamed the bank, the Swiss government and the justice department for allowing close to 22,000 US citizens to get away with hiding $12bn (£7bn) from the taxman in Swiss bank accounts.
On Tuesday the committee had released a 178-page report documenting how Credit Suisse helped US citizens escape taxes using systems which the Republican senator John McCain said were like something out of "a spy novel".
According to the report, bankers filed false visa applications pretending they were tourists and drummed up business at sponsored golf events. One customer's bank statements were passed to him hidden inside a copy of Sports Illustrated.
Clients who visited the bank in Switzerland were whisked to meetings in a button-less, remote-controlled lift where they were advised on the best way to circumvent US tax laws.
About 1,800 Credit Suisse staff worked on the accounts, but only 10 people have been disciplined and none had been sacked, the committee heard.
The Credit Suisse chief executive, Brady Dougan, told the senators that he was blocked by Swiss law from disclosing the names to the US authorities. "So any real idea that the [Swiss] government is co-operating with us is a joke," said McCain, the subcommittee's ranking Republican member.
Levin said that despite a criminal investigation by the US justice department the bank had handed over the names of just 238 people so far. He said he would be pressing the justice department to force the bank to disclose more. "You want to do business here, you have got to comply with our laws," said Levin.
Romeo Cerutti, the bank's general counsel, said: "We would all face criminal indictments and possibly prison terms if we were to hand over these client names."
Dougan, the first US boss of a Swiss bank, said: "To our deep regret, it is also clear that some Swiss-based bankers at Credit Suisse appear to have helped their US clients hide income and assets in the past.
"Although it was not and is not illegal for Swiss banks to accept deposits from Americans, it is absolutely unacceptable for Swiss-based bankers to help US taxpayers evade taxes or to provide them with securities advice in the US without being properly licensed."
He said the bank had made "substantial progress" in taking responsibility for past problems and resolving them. Since 2008 the bank has required US clients to demonstrate tax compliance, he said. The bank had also conducted a thorough internal review.
The practices went on from at least 2001 to 2008, according to the report. In 2011, the justice department told Credit Suisse and seven of its bankers that they were the subject of an investigation, but neither the bank nor the bankers have yet been held accountable, said the senators. Levin said he understood that no requests had been made to extradite the Swiss bankers.
The senators were set to quiz the justice department about the case in an afternoon session.