Pupils as young as six excluded for taking knives into school

More than 300 children have been excluded after carrying blades, including machetes, into lessons

Schools are struggling to cope with a rising tide of violence among children, some of primary school age, according to government figures.

Henry Webster, a 17-year-old school pupil, is so concerned that he spoke out yesterday for the first time since being attacked two years ago by a gang of seven youths, who struck him repeatedly with a claw hammer. Henry was left with brain damage.

Driven by fear or bravado, thousands of children are arming themselves, and hundreds are being expelled for bringing weapons including machetes into class.

This weekend, a primary school child was excluded after the knife he was carrying triggered a metal detector during a scan for weapons at his school in Brent, north London. It is one of more than 300 cases where pupils as young as six have been thrown out of school for carrying or using knives or other bladed weapons over the past five years, according to new figures obtained from 16 education departments across England under the Freedom of Information Act.

The true extent of the problem is likely to involve thousands of children, with 134 departments unwilling or unable to provide statistics on knife-related expulsions. The National Union of Teachers has warned that knives in the classroom are a growing problem.

Sir Alan Steer, the Government's behaviour tsar, called for social workers to be brought into schools to help deal with out-of-control pupils.

Chris Keates, the general secretary of the NASUWT union, said: "There should be a national register of assaults, incidents and exclusions wherever knives are involved, because only then will we know where and how much we need to act to protect pupils and staff. I worry that, by failing to record and monitor incidents serious enough to warrant an exclusion, the authorities are somehow implying that this is not really a big issue. If they want to pretend a school does not have a problem, they are putting everyone who works or learns there at risk."

A spokeswoman for the Department for Children, Schools and Families said incidents with knives in schools were "incredibly rare". She added: "We have given heads tough new powers to conduct hands-on searches for weapons to ensure schools are knife-free zones.

"Schools are also able to screen pupils for weapons using 'arch' and 'wand' metal detectors to protect pupils and staff. We are looking to extend this to drugs, alcohol and other contraband at the earliest opportunity. We are sending out a clear message that bringing a knife into school is a criminal offence and will not be tolerated."

Hammer attack: Henry at 15 was left with brain damage

Henry Webster, now 17, needed emergency brain surgery after his skull was fractured in three places, and has been left with physical and psychological scars. He was attacked on the tennis court at Ridgeway School, Swindon, by a group of seven Asian youths in January 2007, and left with permanent brain damage; 13 young men were convicted over the assault.

"The clearest memory I have was when I was first hit in the back of the head," he said. "It was like my vision shattered, then I remember lots of blood. At one point I was wondering if I was going to survive it... I was just in the wrong place at the wrong time.

"I know that I'm not going to be the same as I was before... but I just try to feel as normal as possible.

"People are sending their kids to school – somewhere that should be almost as safe as your home," he warned. "But everyone needs to realise that it's not as safe as they think it is."