In addition to the issue of cooperation, there are technical obstacles to tapping Skype calls. The way calls are set up and carried between computers is proprietary, and the encryption system used is strong. It could be possible to monitor the call on the originating or receiving computer using a specially written program, or perhaps to divert the traffic through a proxy server, but these are all far more difficult than tapping a normal phone. Calls between a PC and a regular telephone via the SkypeIn or SkypeOut service, however, could fall under existing wiretapping regulations and capabilities at the point where they meet the public telephone network.
The pan-European response to the problem may open the door for the United States to take similar action, Thuy said.
"We have very good cooperation with the U.S.," he said, pointing out that a U.S. prosecutor, Marylee Warren, is based in The Hague in order to liaise between U.S. and European judicial authorities.
The NSA (National Security Agency) is so concerned by Skype that it is offering hackers large sums of money to break its encryption, according to unsourced reports in the United States.
Italian investigators have become increasingly reliant on wiretaps, Eurojust said, giving a recent example of customs and tax police in Milan, who overheard a suspected cocaine trafficker telling an accomplice to switch to Skype in order to get details of a 2kg drug consignment.
"Investigators are convinced that the interception of telephone calls have become an essential tool of the police, who spend millions of euros each year tracking down crime through wiretaps of landlines and mobile phones," Eurojust said.
The first meeting of Eurojust's 27 national representatives is planned in the coming weeks, but precise details of its timing and the location of the meeting remain secret, Thuy said.
"They will exchange information and then we will give advice on how to proceed," he said. Bringing Internet telephony into line with calls on landlines and mobile phones "could be the price we have to pay for our security," he said.