New classified files leaked to Danish media suggest some EU states are allowing US spies to tap data cables in order to intercept the emails, phone calls, and Internet chats of Europeans. Danish media Dagbladet Information and The Intercept made public documents disclosed by former US agent Edward Snowden related to a programme codenamed "RAMPART-A", under which "foreign partners provide access to cables and host US equipment." At least 15 European members have been participating to the program, according to the reports. Among the reportedly willing "foreign partners" are Denmark and Germany.

German authorities last year spoke out against allegations the Americans had tapped German chancellor Angela Merkel's mobile phone.

The EU also backed down from scrapping a data-sharing agreement with the US known as Safe Harbour.

On Wednesday, the Irish high court in Dublin asked the European Court of Justice to rule on Facebook's reported ties and co-operation with NSA filed by an Austrian privacy campaigner.

Australia, Canada, New Zealand, and the UK have already a more robust "Five Eyes" surveillance pact with the Americans.