The tax division of the US Justice Department has urged Swiss banks to support their anti-tax evasion drive or risk prosecution.

The government-brokered risk prosecution program is expected to close in about six weeks.

US Department of Justice assistant attorney general Kathryn Keneally in an interview to Swiss newspaper Sonntagszeitung said: "We want to assure the banks that we are here to speak with them and implement the program."

Meanwhile, Keneally said the US Justice Department will continue to investigate banks which encouraged tax evasion and will seek criminal charges for those which don’t come forward to join the program.

"Our program enables banks and individuals to bring this to an end. Should they choose not to make use of it, we will keep investigating and press charges," Keneally added.

The program will apply to about 100 second-tier Swiss banks, which will have to disclose hidden information and face penalties of up to 50% of the value of assets they managed on favor of wealthy Americans.

The program will not include banks already under US criminal investigation such as Credit Suisse and Julius Baer.

Keneally said Justice Department officials have received requests from Swiss banks to explain the program’s guidelines.

According to the program, Swiss bankers that cooperate with US Justice Department officials will run the risk of being pursued by Swiss prosecutors for breaching the country’s strict banking secrecy laws.