The investigation of an alleged Swiss spy apparently involved in an operation to uncover German tax evaders appears to be widening. The suspect was detained last Friday by the German justice authorities.

Valentin Landmann, the suspect’s lawyer, told Swiss public radio, SRF, on Monday that his client is a security consultant working primarily in the financial sector – also for Swiss institutions.

However, he did not confirm that the 54-year-old man had a mandate from the Swiss intelligence service as alleged by the German justice authorities.

The Swiss defence ministry initially declined to comment, while the foreign ministry said it was aware of the detention of a Swiss citizen in Germany.

Legal proceedings are pending in Switzerland against the suspect, who is accused of handing over confidential client banking data to Germany, allegations rejected by the lawyer.

Landmann said his client had only partly collaborated with German tax investigators who had illegally tried to collect banking data in Switzerland, adding that his client had not given any “valid banking data”.

He said the German arrest warrant against the suspect was based on confidential information from an investigation by the attorney general.

Legal grey area

The head of Switzerland’s parliamentary watchdog, Alex Kuprecht, said the suspect had repeatedly been the subject of discussions with the authorities over the past few years.

Kuprecht added that the parliamentary committee had not been informed about the latest case, but noted that the suspect might have operated in a legal grey area if he had a mandate.

Last September, the Swiss authorities confirmed that a former UBS banker had been charged with selling confidential client details to Germany. His identity has not been revealed.

The allegations centre on the 2012 sale of a CD containing details of UBS customers to the state of North Rhine-Westphalia. The CD pertained to assets worth CHF3.5 billion ($3.5 billion).

Since 2010, the German state of North Rhine-Westphalia has bought the names of Swiss banking clients to determine if they cheated on their taxes.

On Monday, the finance minister of North Rhine-Westphalia, Norbert Walter-Borjans, criticised Switzerland for spying on tax investigators. He said Germany had no choice but to buy banks’ client data if it wanted to crack down on tax cheats.

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