And if the trials prove...

And if the trials prove successful, they could signal a gooey end to dangerous, high-speed pursuits. The technology uses gas-propelled tracker darts which are launched from a squad car"s radiator grille to tag the target vehicle. Officers can then back off and watch the crooks" progress on a computer screen.

Pioneered by Virginia-based company Starchase, the system should allow the police to locate any tagged vehicle without endangering the public or officers with a pursuit. It works by firing a golf-ball sized GPS receiver covered in a gluey compound, which is designed to stick to a car"s bodywork. And the trial is being followed by police forces in Britain.

"The tag adheres to the suspect vehicle and then transmits its location to a central point, which relays it to a computer map display," said company chief Mandy McCall. "Even if fleeing drivers realise they have been tagged, it"s very unlikely they could unglue the dart."

Los Angeles Police Department head William Bratton said: "We believe this technology will give officers yet another tool to minimise the damaging risks associated with high-speed pursuits."

The LAPD intends to test the system for up to six months, after which the maker will offer the darts to other forces.

A spokesman for the Association of Chief Police Officers in the UK said: "Any device that improves safety is always welcomed. Once we have more information we will be happy to investigate any potential benefits the device may have."