The private banking arm of British bank HSBC in Geneva has filed a criminal complaint against a former employee who allegedly stole client data in 2006 and 2007.
The information is said to have been passed on by the information technology employee to French authorities.
In a statement on Wednesday, HSBC said the theft was reported to the company after police surveillance in 2008, adding that “to the best of the bank’s knowledge, the number of names potentially involved was fewer than ten”.
Earlier, the French daily Le Parisien reported that the employee had stolen thousands of secret bank accounts and handed them over to French tax-fraud investigators.
It added that the former employee had fled to France, where he was living under judicial protection.
The statement added that HSBC continued to support the authorities “with their enquiries in this criminal inquiry”.
The head of Switzerland’s Association of Foreign Banks has confirmed that some information was stolen from the Swiss branch last year.
In August French Budget Minister Eric Woerth said he had obtained a list of 3,000 French citizens who held secret accounts in Swiss banks worth about €3 billion (SFr 4.53 billion).
Woerth confirmed receiving the IT employee's information but said he was only "one source" of information.
He said the French authorities were working on 1,400 dossiers, which could bring in an extra €500 million in tax revenues.
swissinfo.ch and agencies