Swiss authorities have searched a house in Geneva and seized computer material in connection with a possible cyber attack on nuclear negotiations between Iran and major powers in the city, Switzerland's attorney-general said on Thursday.A computer virus was used to hack into locations including three luxury hotels that have hosted negotiations between Iran and six world powers, the Russian computer security company Kaspersky Lab said on Wednesday."On 12 May 2015, a house search took place in Geneva and IT hardware as well as software was seized. The aim of the aforementioned house search was to seize respective information as well as the malware; it was of particular interest to investigate whether the malware infected the respective IT systems," the Swiss attorney-general's office in Berne said in a statement.Criminal proceedings have been opened against unknown persons "on suspicion of political espionage", it added without elaborating. A spokesman declined to give any further information on the investigation.In addition, an investigation into alleged spying at the Geneva hotels where Iranian talks were hosted has been ongoing since May 6, AFP reported Thursday.The news site received confirmation that the probe was launched early May by Swiss authorities and followed by a raid May 12, during which computers were seized.It was not verified whether hotels were targeted in the raid.A cybersecurity firm reported Wednesday that it had identified breaches in its software at three luxury Swiss hotels, which had hosted Iranian nuclear talks, from a virus considered a hallmark of Israeli intelligence operations. Kaspersky Lab ZAO said the virus, known as Duqu, allows handlers to monitor activity, steal computer files, and eavesdrop on the rooms in which computers are operating.An Israeli deputy minister dismissed reports of Israel's connection to the virus as 'baseless.'US officials publicly accused Israel of spying on the talks back in 2014 and have repeated those allegations on multiple occasions since. Israel’s intelligence effort, they say, began in 2012, when the Obama administration first opened a covert channel with Tehran.