After violent incidents in which two teenagers were taken to hospital in the past week, experts say adults need to take more responsibility to stop bullying.

Associate Professor of clinical psychology at Auckland University Ian Lambie said while Ministry of Education programmes in secondary schools were good, primary school children needed to be taught that bullying - physical or through technology such as cellphones - was unacceptable. "The earlier you start the better."

And family therapist Diane Levy questioned the message of "shame, humiliation, fear and isolation" promoted in many reality TV programmes, produced by adults but often watched by impressionable teenagers.

Last week a Wanganui Girls' College student was taken to hospital after she was viciously attacked by another student who has been stood down from the school.

The victim was left unconscious after allegedly being stomped on the head. The schoolgirl believed responsible for the assault will appear this week before the school's board of trustees with her parents.

The assault was recorded, and the video later passed to Wanganui police.

Wanganui truancy officer Joff Latus said female secondary school violence was not just a Wanganui problem but was an issue around the world. Wanganui police Senior Sergeant Dave Kirby said girl violence was now on a par with that of young males. "Violent behaviour is not a gender issue any longer."

The Wanganui Girls' College incident follows an attack at Morrinsville College where three girls assaulted a fellow student in a toilet, causing a brain injury.

Levy said she was not surprised at the steady increase in female violence happening in schools. It was part of girls becoming "more equal" in every aspect, including participation in aggressive sports, martial arts and boxing.

This week a 17-year-old was taken to Auckland City Hospital after being repeatedly punched in the head during a schoolyard fight at Lynfield College. The fight was recorded on a student's cellphone and sent to other pupils in the school.

The student responsible for the violence has been suspended and will go before the school board this week.

Netsafe executive director Martin Cocker wants to see a national programme established, similar to the well-funded National Centre Against Bullying in Australia.

Experts say the messages to children about bullying need to be very clear.

Child and family psychologist David Stebbing said parents needed to have a no-tolerance policy.