GENEVA (AFP) - A former Swiss banker fainted on Wednesday at the opening of his trial for breaking Swiss bank secrecy laws for allegedly giving confidential data to WikiLeaks and German authorities, media reported.

The trial of Rudolf Elmer, the former chief operating officer at the private bank Julius Baer's subsidiary in the Cayman Islands, opened and was quickly suspended after he fainted in court, the RTS public broadcaster reported.

The 59-year-old had been questioned by the judge before fainting during a short recess, RTS said.

Elmer, who was arrested 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, was taken by ambulance from the Zurich district court to a nearby hospital, according to the report.

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 widespread 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 accused of handing 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 former 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 has denied any wrongdoing.