Swiss authorities have charged Rudolf Elmer, a former Julius Baer banker, with violating the country's secrecy laws after claiming he released details of client accounts via WikiLeaks.
According to Zurich's prosecutors' office, Elmer had allegedly violated secrecy laws between 2007 and 2011, although he left the private banking group in 2002.
He had allegedly "handed over two disks that contained information on about 2,000 offshore banking clients to WikiLeaks founder Julian Assange."
Swiss authorities said that after investigating Elmer, and detaining him for five months in 2011, it found that he had also offered bank data to the German finance ministry by forging a document that involved his former employer Julius Baer.
Elmer has denied the charges although, in the past, has said he wants to draw attention to financial abuses.
"Elmer sees himself as a whistleblower," said prosecutor Peter Giger to Bloomberg on the telephone. "He has a message he wants to bring across. I am convinced he broke the law in trying to do that."
The Zurich prosecutors' office said Elmer remains free from detention as the case continues.