A new encryption system, which its creators say is unbreakable, got its first test run Wednesday in Vienna, scientists from the European Union project SECOQC announced.

The successful demonstration, developed by the EU's Development of a Global Network for Secure Communication based on Quantum Cryptography (SECOQC) paves the way for it to be used in ordinary communications networks.

"Potential users of this network, such as government agencies, financial institutions or companies with distributed subsidiaries, can encrypt their confidential communication with the highest level of security," said a SECOQC statement.

This kind of network should be commercialised within three years, said the project's Austrian coordinator, Christian Monyk.

The technology works by sending streams of light particles, or photons -- and that, say the scientists who created it, means it is entirely secure, as any eavesdropping would leave traces and immediately be detected.

Encrypted data, including a videoconference, was transmitted via standard optical fibre to six different centres, some as far as 82 kilometres (50 miles).

The demonstration took place during a three-day international conference in the Austrian capital to demonstrate the system.

Until now, quantum cryptography has been used simply to transmit information from one point to another, rather than as part of a network.

It is the result of four and half years of work by 41 partners, mostly universities and research centres, from 12 European countries.

Led by the Austrian Research Centers, the project was sponsored by one of the fathers of quantum physics, Anton Zeilinger from the University of Vienna.

Scientists from Austria, Belgium, Britain, Canada, Czech Republic, Denmark, France, Germany, Italy, Sweden and Switzerland all participated in the 11.4-million-euro SECOQC project.