Deliberate self-harm among adolescent girls is far more common than feared, according to new research by Oxford professor of psychiatry Keith Hawton.

Prof Hawton's findings suggest that levels of misery among teenagers result in worrying levels of violence against themselves.

More than 6,000 pupils, aged 15 and 16, from 41 schools in Oxfordshire and neighbouring counties, were questioned about lifestyle, deliberate self-harm, suicidal thoughts and low self-esteem.

It emerged that seven per cent had carried out an act of deliberate self-harm in the previous year, while deliberate self-harm was almost four times more common in females than in males.

Factors found to have led girls to deliberately injure themselves included drug misuse, depression, anxiety, impulsivity, low self-esteem and recent self-harm by friends or relatives.

Prof Hawton, head of Oxford University's Centre for Suicide Research, said the findings backed the need for school-based mental health initiatives.