An investigation by a U.S. Senate panel says that billions of dollars of taxes in the U.S. are not being paid because Americans have exploited bank accounts in a Swiss bank that the government of the U.S. has not pursued aggressively enough.

The bank, Credit Suisse, is the second largest in Switzerland and has approved banking accounts in Switzerland for over 22,000 clients from the U.S. that total between up to as much as $12 billion, according to a new reports the Senate Permanent Subcommittee for Investigations issued on Tuesday.

The government of the U.S. has only received 238 names of citizens of the U.S. with the secret Credit Suisse accounts or about 1% of the total the committee estimate exists.

U.S. clients were recruited by Credit Suisse to open accounts in Switzerland between 2001 and 2008, helped them to conceal those accounts from the IRS and enable bank employee misconduct, the senate panel asserted.

For over five years, the panel has examined banks’ use in Switzerland of secrecy laws that enable Americans to evade taxes. The focus of the latest report by the panel was Credit Suisse.

The bank did not make any comment following the report from the Senate panel. However, the U.S. Justice Department, in responding to it, said it was currently investigating 14 financial institutions in Switzerland and there will be no hesitation to indict if circumstances merit it.

The subcommittee in the Senate asserted that the government of Switzerland with its world-renowned banking secrecy has been obstructing authorities in the U.S. from learning the bank customers’ names who are U.S. citizens.

The senate report detailed the tactics of cloak and dagger used by bankers at Credit Suisse. The bankers allegedly travel to the U.S. to service accounts secretly and to recruit additional customers. Alleged trips included attending pro golf tournaments in the southeastern U.S. as well as New York’s Swiss Ball that is held annually.

The report said that during breakfast at one hotel, a banker handed bank customer statements to a client hidden inside the pages of a Sports Illustrated magazine.

Credit Suisse is alleged to have filed for visas for its employees that portrayed them being tourists. The bank also is said to have maintained an office in New York with intermediaries who would open offshore companies for some of their customers in the U.S.