By Sean Coughlan BBC News Online at the NUT conference

Teachers want the right to screen children for behavioural problems before they enter school.

This could mean children as young as four having some form of psychological profiling, in an attempt to identify children who could be violent or disruptive.

Delegates at the National Union of Teachers' conference in Bournemouth heard calls for more protection against aggressive behaviour from pupils.

And teachers want head teachers to be given powers to assess children before they start school, where there are concerns over "emotional or behavioural difficulties".

This would apply to both primary and secondary schools - and reflects a growing concern over the difficulties facing schools in managing sometimes disturbed and unstable pupils.

Although some delegates expressed concern that this plan could mean children with special needs being stigmatised and excluded before they had even begun their school lives.

The motion adopted by the unions is not designed to block the admission of potentially difficult pupils, but is intended to ensure that extra support services for such pupils can be put in place.

But where there are no local authority support services available, it raises the prospect of schools challenging the entry of disruptive pupils.

Teachers are also asking for clear guidance that pupils will be excluded from school permanently if they attack or threaten to attack staff or if they carry offensive weapons.

Anti-social

Teachers' unions have become increasingly concerned over the incidents of violence against school staff, with claims that they are bearing the brunt of anti-social behaviour by youngsters.

Speaking at the conference on Saturday, the Education Secretary Estelle Morris highlighted the importance of protecting teachers, and accused some parents of sharing the responsibility for violent pupils.

She criticised a "small group of parents who deliberately chose to take away the right of teachers to exercise discipline".

And she said that there was too little of recognition that school was often the first place in which children found discipline - and that it was sometimes the only orderly place in their lives.