The text alert scheme has been backed by Sarah's parents

It means that if a child is snatched anywhere in Sussex, the police will be able to send a warning to the phone of everyone who has registered.

The project is the second phase of Child Rescue Alert, set up by Sussex Police in November with the backing of the mother of murdered schoolgirl Sarah Payne.

Over 4,000 phones in Sussex have already been registered to receive the messages.

Sara Payne launched a newsflash scheme in November

Among them are all Sussex Police, East and West Sussex County Councils and Brighton and Hove City Council mobiles.

Sussex Police worked with East Grinstead-based company Community Alerts to set up a pioneering system combining text messaging with mapping technology.

It means officers will be able to target phones within a selected area, whether within 100 metres of the site of a suspected abduction or up to 100 km away.

Neighbourhood Watch co-ordinators will now hand out 300,000 leaflets across the county encouraging people to sign up to the scheme.

'Act as extra eyes'

Project manager Detective Chief Inspector Martyn Underhill said: "We need to increase the number of people who can act as extra eyes and increase even further the chance of saving the child.

"People normally have their mobile phone with them and registering that phone to receive an alert is something positive that everyone can do to help."

People can register their phones online at the Child Rescue Alert website.

Under the initial phase of the project, Sussex Police set up a system to send an alert to local radio and television stations as soon as a child is snatched.

They will then broadcast a newsflash giving details of the missing child to the public.

Child Rescue Alert is based on an American system called Amber Alert.