USING satellite technology would be an effective way of tracking sex offenders in Scotland, according to a leading international expert.

The advice from the judge in charge of the tagging of sex offenders in Germany comes as Scotland is expected to introduce the scheme next year, with convicted paedophiles, rapists and others who have committed sex crimes likely to be targeted.

Judge Silke Eilzer, head of electronic monitoring in the state of Hesse and national lead for the GPS tracking of sex offenders in Germany, said it works well, but must be done in conjunction with social work support. Scotland only uses electronic monitoring to impose curfews on offenders.

Speaking on a trip to Scotland to meet lawyers policy makers and judges, Judge Eilzer said: "Just because GPS is available we should not necessarily use it for everyone. We have to look at a target group. It has definite advantages but also has drawbacks, including short battery life. With GPS at best the battery lasts a day.

"We are very careful in Germany about collecting data on people following on from the Stasi. We need probable cause to check where that [tagged] person is and we can not curfew them - even a sex offender - because they have finished their prison sentence.

"What we can do is ban them from entering or leaving certain areas - such as kindergartens or red-light districts."

Scotland is likely to pilot the GPS tracking of certain offenders after the consultation on the future of electronic monitoring.

Germany is currently monitoring 62 people. Some have been satellite tracked for two years. Under their model, locational information on offenders has to be destroyed every two months.

Since satellite tracking started in Germany two years ago, there has been one high profile case of a sex offender abusing a nine-year-old girl while wearing a GPS tag. "The problem is that he was not in an exclusion zone, the battery was charged, there was nothing to alert the monitors, no alarm was raised," Judge Eilzer said.

"With GPS the first aim is to increase someone's inhibitions to not reoffend. It is a new way to try to influence behaviour but it really needs the proper support of social work and probation. It is never enough to just put a tag on someone. They need human support."

Mike Nellis Emeritus, professor of criminology at Strathclyde University, said: "People need to realise that GPS monitoring does not necessarily mean people being followed on a screen all the time.

"As in Germany, it can be used to alert authorities if someone is entering an exclusion zone. For some it used to seem like the George Orwell vision, but that has changed considerably with the fact that almost everyone uses a smart phone. This is just another gadget and can be used in different ways."

A Scottish Government spokeswoman said it was consulting on possible uses for the technology.