Rudolf Elmer, a former executive at Julius Baer, handed over to the site two disks containing information supposedly relating to 2,000 accounts housed off-shore.
Wealthy business leaders, politicians and executives are all thought to be among those high-net individuals with their details featured on the disks, which were exchanged at a press conference in Londonâs Frontline club.
Mr Baer is thought to have sourced the information from a number of other whistle blowers while the data is believed to refer to at least three major financial institutions and their activity between 1990 and 2009.
In an interview with Swiss newspaper Sonntagg, which was conducted ahead of the data handover, he said: âThe documents show that they hide behind banking secrecy, probably to avoid tax.â
The former banker is to appear in a court in Zurich later in the week to face charges of breaking Swiss bank secrecy laws.
Wikileaks is currently using the Frontline Club as its London headquarters.
By Jim Ottewill