Swiss prosecutors said Friday they had opened an investigation into alleged spying on members of the Turkish community in Switzerland by an unspecified "intelligence service".
The Office of the Attorney General told AFP it had "concrete suspicions (of espionage) against the Turkish community in Switzerland (by) a political intelligence service," and said it had opened its probe on March 16, after receiving a green light from the Swiss government.
The prosecution authority however refused to provide details on which specific people or organisation the investigation was targeting.
Earlier this month, Swiss media reported suspicions that espionage activities targeting Turks critical of the Turkish government was taking place at the University of Zurich.
According to the reports, two men at a seminar on World War I-era Armenian genocide -- a term Ankara vehemently rejects -- systematically photographed the participants.
And in mid-March, a member of Switzerland's upper house of parliament Josef Dittli filed a lawsuit accusing two Turkish organisations of spying on Turkish citizens and dual nationals living in Switzerland, and requested an investigation.
His suit singled out the Swiss Turkish-Islamic Foundation (TISS) and the Union of European Turkish Democrats, and said Turkish diplomatic institutions might also be involved, according to the ATS news agency.
The Swiss investigation comes a day after Turkish Foreign Minister Mevlut Cavusoglu discretely visited Switzerland and met with his Swiss counterpart Didier Burkhalter, at a time when Ankara finds itself locked in a bitter row with a number of European countries.
Relations between Turkey and Europe have been severely strained since several Turkish ministers were blocked from campaigning on the continent for a 'yes' vote in next month's referendum on boosting the powers of President Recep Tayyip Erdogan.
Switzerland has not blocked the campaign events, but Cavusoglu did call off a visit earlier this month after the hotel he had booked for a rally refused to host it, and another Turkish politician was forced to change locations several times for a separate rally.
During their meeting on Thursday, Burkhalter "underscored the validity of Swiss law on Swiss soil, urged Turkey to comply with it," according to a statement, which also stressed "Switzerland would rigorously investigate illegal intelligence activities" on its soil.