Even though Microsoft expresses its commitment to protect users’ privacy with every single occasion, the PRISM program revealed this summer continues to cause trouble to the Redmond IT giant.

Citing sources close to the matter, The Guardian is reporting that Skype is now under investigation in Luxembourg following claims that Microsoft handed over user data to the US National Security Agency (NSA), as part of the PRISM program.

Skype, which has its headquarters in Luxembourg, was accused of being used by the NSA for tracking users and wiretapping their conversations, even though Microsoft said that data sharing only took place based on federal requests.

Luxembourg, on the other hand, which has vowed to protect users’ privacy unless state agencies fill in legal requests for specific account, could issue new criminal and administrative sanctions, which according to the same source, might include a temporary ban on sharing users data with US state agencies.

Microsoft hasn’t yet commented on the possibility to be fined in Europe, but Luxembourg’s data-protection chief, Gerard Lommel, confirmed in a report that an investigation is under way.