Knives
The scanners may be set up in schools in major cities
Metal detectors are to be installed at hundreds of schools in England as part of a drive to reduce knife crime.
The measure is included in a government plan to be announced next month to deal with violent behaviour.
The airport-style search arches may be introduced at the some of the country's toughest secondary schools in London, Liverpool, Manchester and Birmingham.
The plan is reported to have the backing of senior police officers and head teachers.
'Responsive policing'
I want young people to know that it doesn't make them safer to carry a knife
Home Secretary Jacqui Smith
They are said to have told Home Secretary Jacqui Smith that the efficiency of the detectors in dealing with knife crime in the worst affected areas outweighed any concerns regarding pupil privacy.
Ms Smith told BBC One's the Andrew Marr show: "I think that it's a good idea if we look at the ways in which in some schools it might be appropriate to use search arches - because I want young people to know that it doesn't make them safer to carry a knife.
"It actually makes them more likely to be a victim."
Shadow Home Secretary David Davis said the installation of scanners in some schools was "long overdue".
"The powers have existed for some time and we have been calling for this for some time. However, while there are hundreds of scanners there are thousands of schools.
"We hope that - for a change - this initiative actually makes it beyond the front page."
Chris Huhne, for the Liberal Democrats, said the move was "sad but necessary" and urged greater use of stop and search powers to combat knife crime.
John Bangs, of the National Union of Teachers, also broadly welcomed the plan, but stressed it would only be appropriate for a small number of schools where gang violence was a problem.
He said: "It should be part of the armoury of keeping schools secure, when the head is worried about gangs outside."
'Knife crime'
He said he was aware of a small number of schools, including one primary school, which already had scanners.
John Dunford, general secretary of the Secondary Heads Association, told the Observer newspaper: "There are schools serving areas where knife crime is high in the community and it's right that these schools take measures to protect pupils, but this is a very small number."
A Home Office spokesman said: "More detail will be available in the Tackling Violence Action Plan which the Home Secretary will publish in the next few weeks.
"We are continuing to tackle knife crime through responsive policing, and prevention projects which provide diversionary activities, training, peer mentoring and education projects."
Ms Smith also said during her interview that the government was looking at whether alcohol was too cheap, following the death of Garry Newlove who was killed by a group of teenagers who had been drinking.
She said: "I think we need to look at whether or not both pricing and promotion is having an impact. That's work that's already under way, and of course we'll respond to what the conclusions of that are."
