THE government has quietly abandoned its “spy-in-the sky” scheme to track paedophiles because the plan has serious technical flaws.

The revolutionary use of satellites to monitor the movements of sex offenders after prison was presented by successive home secretaries as “a prison-without-bars” that would allay the public’s fears about child abusers.

However, officials say plans to launch the system nationwide have been dropped after a pilot found that the signal emitted from the tracking devices could be blocked by clouds, buildings or leaves. It was also lost underground and on some trains.

The Ministry of Justice has decided to focus instead on lie detectors as a means of controlling paedophiles released on parole. The U-turn will leave ministers facing accusations that they have failed to address the threat that communities face from 30,000 registered sex offenders.

The scheme uses technology similar to GPS in cars. An ankle tag broadcasts a radio wave that is then pinpointed by four satellites. But a report on the pilot scheme for sex offenders in Man-chester and one for violent offenders in Birmingham and Hampshire said the signal became confused unless there were at least four satellites in “line of sight” of the tag.

Harry Fletcher, assistant general secretary of Napo, the probation officers’ union, said: “The abandonment of satellite tracking comes as no surprise. It was hugely expensive.” He added: “The polygraph [lie detector] is likely to be of limited value because sex offenders can manipulate outcomes.”

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