PORTABLE computers that take digital fingerprints and compare them against the national police database are being trialled in Waltham Forest Motorists pulled over by traffic police from the Operational Command Unit will be asked to put their fingertips in the machines when they are stopped.

The trial, codenamed Lantern, will use existing number plate reader technology to target vehicles police suspect are stolen or connected with a crime, or drivers whom they suspect to be on the police's wanted list.

But motorists could find themselves being asked for their details because their MOT has run out, their lights are broken, or their car is not taxed or insured.

A Waltham Forest Police spokesman emphasised that drivers would not be asked for their fingerprints unless they were unable to prove their identity.

At present around 60 per cent of drivers stopped do not tell police who they really are.

Giving police your fingerprint is not compulsory, and the police admit that they rely on the goodwill of law-abiding citizens.

The devices take a digital scan of the fingertip, then send the information to the national police database to check if the owner is wanted.

Police sources say that the information is not retained by the machines and not stored in the central database unless a crime has been committed.

Mark Wallace from civil liberties' group, The Freedom Association, said: "Taking a fingerprint of someone before they have been arrested is questionable."

He said he did not believe that giving fingerprints would remain voluntary or unstored.

"Every indication I've seen is that the Home Office will in the long run make it compulsory, which will be quite an infringement of human rights," he said.

MP for Walthamstow, Neil Gerrard, also said he would be concerned if the Government made it compulsory but added that he thought there was no sign of that happening.

The police spokesman said that if the trail was successful, officers on the beat may get the devices and use them to target people who looked suspicious.