Nearly half of new teachers have not had enough training to deal with violence in the classroom, a survey showed today.
Figures seen by the BBC also suggest two-thirds of newly qualified teachers have received no clear guidance on restraining violent students.
The Association of Teachers and Lecturers (ATL), which carried out the survey, has called for such training to be made compulsory.
According to the union, 49 per cent of newly-qualified teachers and probationers in England, Scotland, Wales and Northern Ireland felt they had not had enough training to deal with challenging behaviour.
One in five said they had been provided with clear guidance on restraining violent pupils, with nearly 30 per cent saying the area had not yet been covered in training.
Sharon Liburd, from the ATL, told the BBC: "These violent confrontations can erupt very very quickly, they (teachers) need to be clear about what sort of steps they can take to try to stop the situation from escalating, if they have to physically intervene and how in fact they do that."
The ATL surveyed 1,001 of its members across the UK.
A spokesman for the Department for Children, Schools and Families said new teachers were given support to ensure they had the skills they needed.
He said: "Good behaviour and an atmosphere of respect should be the norm in all schools.
"In his recent review, Sir Alan Steer said that behaviour standards have improved and are good in the majority of schools.
"We are determined to tackle poor behaviour and raise overall behaviour standards - that is why we have given schools clearer and stronger powers than ever before to ensure good school discipline."