Police in the West Midlands have developed software to trace people accessing sexual images of children on the internet.

The computer package sets up dummy internet sites, which apparently contain child pornography.

But users going to the police sites are instead warned of the penalties in viewing the material, while officers trace their internet address.

Detectives believe the technology will help catch paedophiles and scare-off those viewing such material for the first time.

It's quite simple, but works just like a magic trick

Detective Inspector Darren Brookes

The dummy sites, run by the police, are designed to respond to the key words typically used by paedophiles searching for child sex sites on the internet.

Users clicking on the web pages are given repeated warnings they could face arrest and imprisonment.

Police are able to trace the home address of those who ignore the warnings.

"It's quite simple but works just like a magic trick," said Detective Inspector Darren Brookes, of West Midlands Police.

"For those searching for these sites, there's no telling whether they might actually be accessing a police site and may end up with the police knocking on their door.

Arrests made

"The dummy sites are described in full so people can't access them by accident," he said.

"This will help us trace paedophiles, but also scare-off those that have been thinking about viewing this material and have just begun to put those thoughts into action."

The Jill Dando Institute laboratory will be in West Bromwich

He said the software had been operating for six months and had already helping in the arrest of several people.

He said information gathered would be passed on to police forces in the UK and across the world.

West Midlands Police will soon be working closely with the first laboratory set up by the Jill Dando Institute of Crime Science in West Bromwich.

The University College London-based institute said it chose the site because West Midlands Police has a highly-sophisticated database of crime, evidence and forensics.

New methods

The institute was set up after the BBC's Crimewatch presenter Miss Dando was murdered outside her London home three years ago.

The laboratory for analysing crime will be based at West Bromwich Police Station's old social club.

Experts based at the unit will study a range of subjects, from criminology to statistics, with the aim of establishing new methods to reduce and detect crime.

The laboratory is expected to be operational by September.