MINISTERS should consider monitoring sex offenders by GPS, according to a report into the case of a man who tried to murder a woman so he could abduct and rape her young granddaughters.

Ryan Yates attacked the 60-year-old woman with a knife in an Aberdeen park, but she fought back to try to protect her granddaughters who were aged two and eight. He carried out the attack just days after being released from prison where he had been serving a sentence for a sexual offence.

Just two days before the incident in October 2009, and four days after Yates had been freed from jail, the authorities obtained a court order banning him from accosting females in public.

But a report into the way the authorities dealt with Yates said those monitoring him were "limited in their ability to manage the risks" he posed before this was granted.

The significant case review stated that had the sexual offences prevention order and other powers been in place, "opportunities to intervene and return him to custody may have been acted upon". The report made a number of recommendations in the wake of the case, including calling on the Scottish Government to consider introducing a GPS tagging system to monitor high-risk offenders in the community.

It said: "This would allow for tracking the movements of an offender and zoning areas he or she would not be allowed to enter, such as parks and school areas."

It also urged ministers to consider changing the law to allow for applications to be made for life-long restriction orders on offenders who have already been jailed, if they are assessed as posing a high risk of re-offending before their release.

Yates, who was 30 when he was sentenced, was made the subject of a life-long restriction order for his attack on the grandmother, with judge Lord Pentland telling him he would probably never be released.

The report further recommended the Scottish Prison Service review its treatment programmes to directly address those who have a "sexual preference for children or sexual violence preferences".