It is loaded onto existing mobile devices that have a GPS chip, such as a PDA. If the users get into trouble, they hold a key on the device down for three seconds to quickly send an alert. Their exact location is then automatically sent to a control centre, which is manned 24 hours a day.

Andrew Overton from VeriLocation said: "Once the alarm has been raised, the control centre will continue to track the location of the device and pass that information to police. It is a stunning improvement in personal safety and one that is highly recommended for lone workers in the UK, especially those working in remote locations or in vulnerable situations."

The personal tracking software can also be used by businesses to track the location of a device at any time, get alerts when it enters certain areas, and even generate information such as mileage reports. The information generated by the device is viewed on a normal Internet browser. Main users of the system are councils, health workers, field based engineers or sales support staff, vulnerable workers, and family members.

There are no "Big Brother" concerns with VeriLocation's personal tracking, as the software can be clearly seen and switched off by the device user. VeriLocation trialled the personal tracking of devices last year, when it gave devices to two celebrities taking part in a charity cycle ride for Sport Relief. The public used the Internet to track the location and progress of football legend Alan Shearer and TV presenter Adrian Chiles.