U.S. lawmakers push authorities to seek extradition against Swiss residents who were charged with helping Americans evade taxes.

Our correspondent Andreas Frank reports: In an open letter, Sen. Carl Levin and Sen. John McCain, who lead the Senate’s Permanent Subcommittee on Investigations, urged the Justice Department to “at least attempt” extradition proceedings against indicted Swiss bankers. The U.S. Senators seek extradition of about 30 Swiss bankers and others who are charged with enabling offshore tax evasion and haven’t appeared in federal courts. Most of them “apparently live openly in Switzerland, having avoided trial on their alleged crimes for years,” Messrs. McCain and Levin said.

A Justice Department official said extradition proceedings would be a poor use of resources. Because aiding tax evasion is not considered a crime in Switzerland, the country is unlikely to honor U.S. extradition requests, the official said. Instead, the department is focused on other ways of pursuing tax evasion cases, the official said citing the October arrest in Italy of former UBS AG banker Raoul Weil.

Weil, who was arrested Oct. 19 after checking into a hotel in Bologna, Italy, waived extradition. Raoul Weil was released on $10.5 million bail in December after appearing in a Florida courtroom to face a 2008 indictment.

Even if the extradition request is denied, Messrs. McCain and Levin wrote, “it will inform both Switzerland and its citizens that the United States is ready to make full use of available legal tools to stop facilitation of U.S. tax evasion and hold alleged wrongdoers accountable.”

The letter is the latest criticism from lawmakers, who say they’ve grown impatient with the pace of U.S. investigations against Swiss banks. At a Senate hearing last month, Mr. McCain faulted the Justice Department for being “incredibly slow” in pursuing Swiss bankers. In 2011, the Justice Department indicted seven Credit Suisse Group AG bankers on tax evasion charges, but none had yet faced trial until very recently.

There are signs that the Justice Department is preparing to get tougher with Swiss banks. Last week, in a surprise development, former Credit Suisse banker Andreas Bachmann returned to the U.S. to face a 2011 tax evasion indictment. Mr. Bachmann admitted to helping Americans hide their assets, in exchange for leniency and being allowed to return to Switzerland before sentencing.
Senate Levin & McCain Letter