Rudolf Elmer, the former chief operating officer at the private bank Julius Baer's subsidiary in the Cayman Islands, has been charged with "repeated violations" of Swiss bank secrecy laws, the prosecution said in a statement.
Elmer has been under investigation since his arrest in 2011 after he publicly handed two CD-ROMS to WikiLeaks founder Julian Assange, claiming they held secret data on 2,000 alleged tax-dodging bank clients.
The former banker, who was dismissed from Julius Baer in 2002, said he wanted the world to know the truth about money concealed in offshore accounts and wide-spread tax evasion.
Elmer insisted a few months after his arrest however that the discs contained no secret information and that he had simply wanted to make a "symbolic" point.
He is believed to have handed over a first set of bank client data to WikiLeaks in 2007 in his stated quest to expose the system, which has since come under massive international attack and been all-but dismantled.
The ex banker is also accused of handing over documents to WikiLeaks in 2008, and of offering bank data in 2009 and 2010 to German authorities, who turned him down.
Elmer, already found guilty by a lower court in 2011 of breaching Swiss bank secrecy laws – shortly before the Assange event – denies any wrongdoing, according to Wednesday's statement.
The prosecutor's office told AFP that it had gathered "additional information" which showed the former banker had broken Swiss law.
A date for Elmer's new trial has yet to be set.