US authorities have been able to bring charges against 60 people accused of hiding $184m (£122m) from the taxman after the Swiss banker who allegedly helped them hide their money accidentally posted a list of his clients.

Prosecutors said the only reason they had been able to identify the alleged tax avoiders was because Beda Singenberger's client list ended up in the hands of authorities.

Assistant US attorney Dan Levy said: "[Singenberger] was sending mail to someone in the United States, and apparently in error he included a list of US taxpayers. The government has mined that list to great effect and prosecuted a number of people who were on that list."

Singenberger's client list has already led to the prosecution of Jacques Wajsfelner, an 83-year-old who pleaded guilty to hiding $5.7m from the internal revenue (IRS) earlier this month.

At Wajsfelner's sentencing in a New York court, Levy told the judge that the list was the only reason Wajsfelner had been identified and prosecuted.

"People who hide money in Switzerland are extraordinarily difficult for law enforcement to identify," Levy added, according to Bloomberg.

Wajsfelner's lawyer Jeffrey Denner said the list had "put a lot of people in the frying pan".

It is not clear how the list – which included clients' names, addresses, Swiss bank accounts and details of how they were hiding their money from the IRS – ended up in the hands of prosecutors.

Singenberger, who hid money in offshore accounts with names such as Real Cool Investments and Lucky Overseas Ventures, has been charged with conspiracy.

Jeffrey Neiman, a former federal prosecutor, said: "It proves that no matter how hard clients try to conceal assets overseas, darn human error can always get in the way."

• This article was amended on 30 April 2013 because the original said Jacques Wajsfelner was jailed. Wajsfelner was placed on probation, but not jailed.