Police radio network finally works on Tube

The £140 million Airwave system has become fully operational after the technology which allows it to function was switched on at the last two stations that had still to be connected: Bank and Leicester Square.

The breakthrough means that one of the key problems faced by emergency staff during the 7/7 London bombings - the inability of police and ambulance workers to communicate properly while at the bomb sites - has now been solved.

A formal announcement is due to be made shortly at an official launch, which is expected to be attended by Mayor Boris Johnson, Home Office ministers and senior police.

Officials said the installation of the system was a vital step in improving the safety of Londoners.

"It is now working everywhere and working extremely well and that is very good news for London," said one source. "The reception is excellent and it means that the problems that we faced before in communicating underground should be behind us."

The completion of London's Airwave system underground comes nine years after the technology, which is being used by police forces across the country, was first commissioned to provide officers with a clearer method of digital vocal communication and the means to transfer data and encrypted information.

A key requirement in the capital was that the system worked underground - as highlighted after the King's Cross fire of 1987 and the 7 July attacks in 2005.

Reports produced for the London Assembly and the Home Office following the 7/7 bombings raised strong concerns about the absence of full underground radio coverage and listed it as a priority reform necessary to protect Londoners during any future attack. Despite this, a series of delays had blighted the introduction of the system, which was originally scheduled to be completed by March 2006.

Critics also expressed concern that it might not provide sufficiently reliable radio coverage in key areas, including parts of the Tube, moving vehicles and some buildings.

Supporters insist, however, that the system - whose introduction has been overseen by the Government's National Policing Improvement Agency - is operating successfully and provides officers with a much clearer and more reliable method of communication than their previous police radios.