The number of girls sentenced by Swiss courts rose last year by more than seven per cent, despite an overall drop in juvenile convictions.
Experts say the figure reflects a growing tendency among girls towards more aggressive behaviour against property and people, something traditionally seen as a male preserve.
Figures released by the Federal Statistics Office on Wednesday show that the number of convicted girls aged up to 18 rose from 2,710 to 2,917. They accounted for just over a fifth of juvenile crime.
This compares with an almost four cent drop in the number of male convictions in the same age category. Overall, juvenile convictions fell from 14,343 to 14,106 last year.
François Ladame, head of the adolescent psychiatric unit at Geneva University Hospital, told swissinfo that the past decade had seen a noticeable rise in outward aggression by young women.
He said that whereas in the past they had tended to bottle up frustration and anger, now they were increasingly releasing it in much the same way as their male counterparts.
"Today we are seeing more and more girls in juvenile detention centres whereas 30 years ago this was very much the exception," he said.
"Girls are increasingly attacking property and people, and adopting what has traditionally been seen as male behaviour. The lines between the sexes have become somewhat blurred and for me this is quite worrying."
To illustrate this, Ladame noted that boys were adopting behaviour traditionally seen as exclusive to the female domain, such as eating disorders.
Show of strength
Over the past five years crime committed by girls has climbed by 27 per cent, whereas the male conviction rate is only seven per cent higher than it was in 2001.
Zurich-based juvenile lawyer Christoph Hug told the Blick newspaper that many young girls felt they were not being taken seriously enough.
"Many of them have problems at school and also at home," he said. "They are demonstrating strength through violence and want to show who's master."
The way to deal with violent girl gangs was to act immediately and isolate the ringleader, he added.
Among adults, the number of convictions last year fell for the first time since 1996 to 92,917 – a drop of 4,384 on the previous year.
This was assisted by an eight per cent decline in road offences and a three per cent fall in drug offences.
Men made up 86 per cent of convicted criminals in 2005 and foreigners accounted for half the total. Suspended sentences were the most common form of punishment, followed by fines and then prison.
swissinfo, Adam Beaumont
Convictions in 2005:
Adults – 92,917
Men, 79,562; women, 13,355
Youth – 14,106
Boys, 11,189; girls, 2,917
Convictions in 2004:
Adults – 97,301
Men, 83,577; women, 13,724
Youth – 14,343
Boys, 11,633; girls, 2,710