More than 20 different railway signalling systems throughout Europe will have to be changed and a new system will have to be progressively introduced, Danish transport minister Henrik Dam Kristensen has warned.

Doing away with national standards will facilitate a smooth and uncomplicated passage of trains across borders, he said, and the European Rail Traffic Management System (ERTMS) will make the railways much more competitive as a means of international transport, he told the Community of European Railways.

Most new lines are now built with ERTMS which has also been adopted as the standard in other parts of the world.

Denmark has implemented ERTMS on its entire rail network, the first European Union state to embrace the technology on such a large scale.

But Mr Kristensen said the absence of a common signalling system in Europe remains a major challenge.

In some countries, Belgium and Spain for example, ERTMS is being introduced to run alongside the existing system.

In Britain, Network Rail is preparing the way for ERTMS by building a nationwide communication system for the network. It will replace the existing analogue systems, including cab secure radio, which has been used since 1986.

The new railway communications system (RCS) involves putting up 2,500 masts and using GSM-R digital technology similar to that used in mobile phones.

RCS will cover 100% of the network, including tunnels and cuttings. It is already in use on the West Coast main line between Crewe and London, in Strathclyde and on the Cambrian line in Wales.

RCS provides secure communication between drivers and signallers but will also provide better information for passengers.

It will be used more intensively as ERTMS comes into use around Britain. ERTMS is currently being tested between Shrewsbury, Aberystwyth and Pwllheli.

It will be installed during the Thameslink signalling upgrade, paving the way for 24 trains an hour in each direction in the London Bridge "bottleneck" area.