The Youth Justice Board (YJB) said violence against the person by under-18s leapt by 39%, from just over 40,000 offences in 2003/04 to more than 56,000 in 2006/07.

The figure included a 50% rise in violence by girls, and offences ranged from common assaults to murder.

Robberies committed by under 18s also saw a large rise - up 45%, from 4,740 to 6,855 a year.

Other crimes which saw significant increases were criminal damage (up 32%) and public order (up 17%).

At the same time, there has been no change in the number of child criminals sent to prison, with numbers running at about 7,000 a year.

The biggest change in the way young criminals were dealt with was a sharp rise in the number handed community sentences - up 26% over three years to 39,700.

Nearly 100,000 child offenders were dealt with by "pre-court disposals" - a slap-on-the-wrist by police. The category rose by 23% to 96,000 from less than 79,000 three years ago.

In figures previously leaked last week, the report also showed the number of crimes committed by girls has risen by a quarter in three years - possibly linked with alcohol.

Girls committed 59,236 crimes in 2006/07, up 25% from 47,358 in 2003/04.