Police rely on 6,000 cameras across Tube network to cut crime

Plans are in place to double the number in use by 2010 as part of its campaign to minimise petty crime, but also to deal with the increasing threat of terrorism. All but 15 of the cameras use traditional analogue technology involving tapes. The small number of newly installed devices use the digital system. A spokesman said the new technology would be employed from now on wherever Tube stations were being refurbished.

The images from the cameras are normally kept for 14 days before being erased or taped over, management said.

A spokesman said that the police made regular requests to see footage as part of their investigations, although the vast bulk of such requests involved criminal rather than terrorist activity.

Senior managers say installing the cameras had helped to reduce crime on the network and that more devices would mean less crime.

Modern coaches such as those on the Northern and Jubilee lines are equipped with the technology, but there are fewer cameras on older rolling stock on other routes.

London Underground has been experimenting with "smart" digital cameras which can automatically spot "abnormal" events. The equipment can be programmed to detect suicide attempts, overcrowding, suspect packages and trespassers. It is hoped that by automating the prediction or detection of such events, Underground security staff, who often have to monitor as many as 60 cameras, can take preventive action.

While some senior managers are keen to see this equipment used throughout the network, it is not clear who would fund such an initiative.