Judges sentencing young people for robbery should take account of pressure on offenders from fellow gang members, according to guidelines issued yesterday.

The Sentencing Guidelines Council (SGC) lists "peer group pressure" as one of the mitigating factors that can reduce the sentence on a young offender convicted of mugging. It applies also to youths convicted of robbing a small business or taking part in a "less sophisticated" commercial robbery.

By contrast, the ringleader can expect a higher sentence than others in a group.

A young offender who uses minimal force or takes little property should receive either a community order or a

12-month detention and training order, the guidelines say. Production of a weapon or injuring the victim will earn a young offender between one and six years. If a youngster causes serious injury by using significant force or a weapon, his sentence will be between six and 10 years.

The equivalent sentencing ranges for adult offenders are up to three years' custody for cases involving minimal force or theft; two to seven years' imprisonment if the attack involves a weapon or force; and seven to 12 years' custody in the most serious cases.

The new guidelines take effect on Aug 1. By law, courts in England and Wales must "have regard" to them.

Under existing case-law, robbery involving physical violence in a person's home will lead to a sentence of 13 to 16 years or more. The most serious commercial robberies are punished with 20 to 30 years. Dangerous offenders may receive life sentences.

The SGC says it is not recommending a major shift in current sentencing practice.

Figures for 2003-04 show that one in three offenders aged 15 received a custodial sentence, rising to two in five for 16-year-olds and three in five for 17-year-olds. Those aged 18 to 20 received custodial sentences in five out of six cases, while adult offenders over 21 were imprisoned in eight cases out of nine.

Group pressure was not one of the mitigating factors for young offenders listed in the original draft guidelines. However, MPs on the Home Affairs Select Committee suggested in March that the issue be taken into consideration.

The SGC said: "There may be factors which are of greater significance in cases involving young offenders, including: age of the offender, immaturity of the offender and group pressure."