London Mayor's office has urged schools to install knife "arches" and introduce hand-held scanners to tackle knife crimes among the youth.
Kit Malthouse, the deputy mayor for policing, said the issue was "very sensitive" but it would "make children safer". But a teachers' group warned of "fatal consequences" if school staff were forced to search pupils.
This year 16 teenagers have been killed in London, of which 12 were stabbed.
College of North East London in Tottenham was among the first colleges to install knife arches in 2006 while Merton College in Morden introduced the scanners this February.
John Troake, headteacher for Haling Manor High School, said: "Politicians constantly focus on what's going on in schools and seem to ignore the 19 hours the young people are out in the society."
The National Association of Headteachers' (NAHT) said: "Installing metal detectors in schools would result in staff having to challenge pupils suspected of carrying weapons. This is a high risk area which could result in fatal consequences.
"This new power should not be implemented as most school staff do not have sufficient skill, knowledge and understanding to reduce risks to an acceptable level." It added that safety of staff as well as of students was "paramount" and said schools needed to develop a plan with police to tackle youth crime.
It appears that teachers do want to help society in dealing with knife crime and are against having metal detectors in schools, they seem to forget they are there to educate our children and this must be part of the education they receive.
I did like statement of John Troake though, but he doesn’t live in the real world, kids carry knife on the street and in schools therefore we must have some mechanism for detecting weapons in these areas. Metal detectors are being deployed at tube and rail stations as a deterrent so we must have them in schools as well. One point I do agree with is that is mustn’t be left to teachers. I believe the police should have dedicated teams that randomly visit schools with this equipment. Or we have them in all schools and have security teams in place at each school with the power to search pupils.