An employee of Basel-based private bank, Sarasin, has been arrested after leaking private data relating to the family of the chairman of the Swiss National Bank.

An employee of Basel-based private bank, Sarasin, has been arrested after leaking private data relating to the family of the chairman of the Swiss National Bank.

The stolen data, concerning currency transactions by the family of Philipp Hildebrand, was handed by the employee to a lawyer with close links to the Swiss People’s Party (Schweizerische Volkspartei, SVP), the Swiss bank announced this morning. The SVP is a right-wing party which has been a critic of the management style of the bank.

According to the employee, who worked in IT support, this lawyer then arranged a meeting with National Councillor Christoph Blocher, which took place on 11 November 2011. Blocher is the former leader of the SVP who still has a heavy involvement in the party.

Sarasin said that the employee had handed himself over to Zurich Cantonal Police on 1 January 2012, and admitted his criminal misconduct to the bank yesterday.

The employment relationship between Bank Sarasin and the employee has been terminated with immediate effect. Hildebrand has been personally notified, said the bank.

“Bank Sarasin is extremely regretful about this incident and has apologised to the client for the considerable unpleasantness caused by the infringement of bank-client confidentiality. The bank condemns the misuse of confidential bank data for political purposes in the strongest possible terms,” said Sarasin in a statement.

Bank Sarasin has informed the Federal Financial Market Supervisory Authority and reserves the right to take legal action. Because of ongoing investigations, no further details can be published at this time, said Sarasin.

This morning’s news follows a statement made last month by SNB’s supervisory board, attempting to quash rumours about the central bank president's wife making personal gains ahead of the introduction of a floor in the Swiss franc’s exchange rate against the euro. In December, the bank said an investigation into dollar transactions made by Hildebrand’s wife in August had concluded that the rumours were baseless. 

The Swiss central bank enforced a minimum exchange rate of SFr1.20 ($1.28) against the euro in September 2011, after the franc soared to record highs against the dollar and the euro in August.

Local newspapers NZZ and Blick have reported that Hildebrand's wife Kashya made a gain of around SFr60,000 ($64,337) from trading dollars.

The bank confirmed that “Kashya Hildebrand, a former currency trader who now runs an art gallery in Zurich, bought an unspecified amount of US dollars for herself and her daughter” but said that the probe had revealed no misconduct, according to Reuters. 

The news is likely to see the SNB fall under increasing pressure to provide transparency, as the bank’s regulations are currently not a matter of public record.