Schools have a vital part to play in helping vulnerable teenagers avoid falling into a life of crime, the Princess Royal believes.

She told a conference in Bristol yesterday she was concerned that a significant proportion of young people who were not at school or work would go on to become prolific offenders.

More should be done to help the ten per cent of 16-18 year-olds classed as Neets – not in education, employment or training schemes – Princess Anne said.

"Schools are a safe place in which they can learn the social and emotional life skills they need," she said.

Therefore, the princess said, schemes to help prevent at-risk teenagers from being excluded from school were to be encouraged.

She was speaking at a conference to mark a successful three-year pilot programme in eight Bristol secondaries called Restorative Approaches in Schools.

It has seen the number of pupil exclusions plummet as behaviour has improved. Restorative approaches have been used to tackle

incidents of abusive behaviour, fighting, bullying and poor attendance.

Princess Anne, who has had a lifelong interest in crime prevention and has been a supporter of restorative methods – which bring parties together to deal with difficulties at grassroots level - for some years, told the event at Brislington Enterprise College that almost half of all crimes were committed by a hard core of prolific offenders.

Most of these had troubled backgrounds, including drug and alcohol abuse, parents in custody, no settled place to live, or being in care. Often this led to them dropping out of school and becoming Neets.

Bristol has about 1,000 Neets. The latest Government figures show 220 in Bath and North East Somerset, 230 in North Somerset and 390 in South Gloucestershire .

"A significant proportion of Neets will move on to become prolific offenders," the Prrincess Royal said.

"The school is a very important centre where the process of changing that can start. You can't change the history of a child's early development years and you can't do much about parental or sibling criminal records.

"I suggest you can do something to ensure that young people complete and get something of value from the education that is being offered."

Using restorative approaches in schools could help teenagers learn how to live in a community with people of different cultures and backgrounds, to value and respect other people, to handle authority and people with different points of view and to deal with conflict, the princess said.

It was a method that appealed to young people as it put them at the heart of the problem-solving, rather than just making them the problem.

"Restorative approaches are not the only answer but they do have the potential to change attitudes and perspectives of all members of the school community," she said.

The conference heard that the three-year Bristol programme had involved training more than 1,200 people, including about 80 students as well as school staff at all levels. At least 400 conferences had been held to tackle incidents at all levels, including interr-student conflict, disputes between students or parents and staff or schools, and inter-staff disagreements.

The aim now is to extend the approach to other secondary schools and to primary schools.

Sir Charles Pollard, a former Chief Constable of Thames Valley Police, who developed restorative justice for tackling young offending and neighbourhood policing, chaired the conference.

He said a youngster excluded from school was eight times more likely to get into serious trouble with the law than one who was not. Keeping children in school protected them from criminal influences outside, he said.

The conference also heard from, among others, Lynette Newman, restorative justice champion at Brislington Enterprise College; Brigid Allen, vice principal of Bristol Brunel Academy and Helen Holman, head teacher of Orchard School. All the schools have had major success in reducing exclusions.

Students from BEC and Orchard School gave presentations. The BEC post-16 students were Elliott Sherwood, Carly Mattock, Georgia Willcox, Lily Bland, Alice Lamb, Shannon Knee, Jessica Stewart and Aalec Sleigh. The Orchard Year 10 students were Tom Hellin, Lewis Perrett, Krescaa Aambata, Angela Chapman, Dre O'Garra Smith, Ayesha Britton, Aideroes Mohammed, Nathan Lee, Oliver Kimberley, and Sarah Barter.