Israel attempted to use a sophisticated virus to spy on nuclear talks between Iran and P5+1, according to a report released Wednesday – by hacking into the servers of hotels where talks were being held. 

Cybersecurity firm Kaspersky Lab ZAO found the hotels on a list of European servers hacked by the virus, identified as a version of Duqu, while scanning its own systems after finding it had been hacked. 

Thousands of other hotels were clean, it told the Wall Street Journal – and the firm later deduced that the nuclear talks were the only common denominator for the luxury hotels. 

Kaspersky officials allegedly did not name Israel as the official source for the virus, but noted there were subtle signs implicating it, including the name of the virus as “Duqu Bet” (Hebrew: Duqu 2). 

The firm has reached out to the Federal Bureau of Investigations (FBI) over the report; the FBI has so far remained silent on confirmation of the report’s findings, but one senior congressional official said the matter is being taken seriously. 

Experts believe Duqu, first discovered in 2011, is used to carry out Israel’s most delicate intelligence-gathering projects. 

Israel vehemently denied spying on talks when the Journal released a similar report in March.

In that report, Israel had been accused of using unspecified means to acquire information “from confidential US briefings, informants and diplomatic contacts in Europe.”