Bank Sarasin has lodged a formal complaint against the Swiss weekly magazine which broke the story concerning one of its former employees stealing bank data about former Swiss National Bank head, Philipp Hildebrand.

Die Weltwoche has been accused by the Swiss private bank of “erroneous reporting”. Today Sarasin lodged a formal complaint with the Swiss Press Council against the privately-owned Swiss publication, it said in a statement.

“The complaint concerns Weltwoche’s erroneous reporting relating to the violation of bank-client confidentiality by a former IT support employee of Bank Sarasin,” the bank said in a statement.

“Bank Sarasin believes Weltwoche seriously failed to meet its journalistic duties in various respects in the knowledge that this would damage Bank Sarasin’s reputation and the reputation of the client advisor wrongly given as a source.”

“Not only did Weltwoche fail to check its own source adequately, but in the edition of 5 January 2012 it deliberately ignored information from Bank Sarasin and the opportunity to talk to the bank, which would have meant the erroneous reporting could have been corrected beforehand. It also failed to publish corrections in subsequent editions,” the statement continued.

Local media reports say that lawyers for Philipp Hildebrand may take legal action and sue the publication for violating privacy laws, and that Sarasin may take a similar course.

Sarasin said in a press release earlier this month: “Bank Sarasin reserves the right to take further legal action. In particular it could make a civil claim for damages and/or make a complaint to the Swiss Press Council about erroneous reporting relating to Bank Sarasin in a Swiss weekly newspaper.”  

The Zurich-based publication is owned by Roger Köppel and publishes commentary from high profile right-wingers.

Sarasin, the private bank which last week announced it had fired an employee who illegally disclosed data about Swiss National Bank head Philipp Hildebrand, has provided further information on the case that has rocked the Swiss financial system since it first broke earlier this month.

According to a statement from the bank, a lone employee in Sarasin’s IT support department passed on the data concurring trades made by Hildebrand's wife to a third party. The employee, who has since been fired, had no contact with Hildebrand and the SNB president’s personal client advisor and was "never at any time put under pressure by Mr Hildebrand," the bank said.

The data was stolen by taking screen shots of the Hildebrand family’s portfolio and of currency transactions, it said.

Earlier this month Hildebrand said he will stay in the job and did not abuse his position after his wife traded two currencies a few weeks before the SNB moved to cap the Swiss franc versus the euro. “I acted not only according to the rules, but also in an appropriate manner,” he was quoted by media reports as saying at a press conference in Zurich a fortnight ago. His wife, Kashya Hildebrand, spent SFr400,000 to buy $504,000 on 15 August, three weeks before the SNB capped the currency at €1.20.

The affair has raised question marks about the security of client information as held by Swiss banks, which operate under a fierce law making it a criminal offence for bankers to disclose client details. Last year, banks such as Julius Baer, Credit Suisse and HSBC’s Swiss private bank were hit by stories about losses of client data.