BB guns have been brought in to some schools

About 20,000 children will be polled in secondary schools in areas covered by Operation Trident, the Metropolitan Police's crackdown on gun crime in black communities.

Teachers have been voicing fears about children carrying weapons and some have called for security checks at school.

In Wales, a recent guns amnesty aimed at schools yielded 50 airguns.

The survey will be carried out in schools in Hackney, Haringey, Lambeth, Brent, Southwark and Newham by the charity Communities That Care.

The schools involved, which are volunteering to take part, will include state and independent schools as well as units which teach children excluded from mainstream schools.

Fashion culture

The announcement comes amid several reports of children bringing weapons to school.

Detective chief superintendent John Coles told the Times Educational Supplement: "We have seen a development, not just in black communities, of a fashion culture for some kids to be carrying a gun. It is seen as cool."

A survey of 160 teachers by the NASUWT teachers' union last year found that one in 10 had caught a child with a gun in the classroom.

At present we only have anecdotal evidence of why young people become involved in crime Met spokesperson

The police say the aim of the survey - which is anonymous - is to find out why some children get involved with crime or anti-social behaviour.

A spokesperson said: "Factors may include their environment, peer pressure, schooling and other issues.

"Equally the survey will identify those factors, which can prevent a young person from becoming involved in criminal or anti-social behaviour."

The police say they will use the information to try to reduce crime.

"At present we only have anecdotal evidence of why young people become involved in crime and anti-social behaviour," the spokesperson said.

"It is hoped it will provide a holistic overview as well as highlight issues that may need to be addressed in particular localities.

"We will then be able to share it with our partners in order to introduce preventative measures."