Parents and pupils who assault teachers will face tougher sentences under government plans to clamp down on violent crimes.
The Home Office meant to include the proposal in the Violent Crime Reduction Bill this week but dropped it at the last minute.
However, Home Office officials said that they would be exploring ways of lengthening prison sentences and increasing fines for those who attack teachers and other public service workers with the Sentencing Guidelines Council.
The sanctions have been welcomed by the NASUWT, Britain's second biggest teaching union, which estimates that a teacher is attacked every seven minutes.
Chris Keates, general secretary, said: "Stiffer penalties not only send out a powerful warning to would-be assailants but give a strong message to teachers and heads that they have the Government's backing in maintaining good order and discipline."
The Bill will give new powers to heads to search pupils they suspect are carrying knives and guns.
The National Association of Head Teachers and the NASUWT said that such searches could put its members in danger.
But John Dunford, general secretary of the Secondary Heads Association, said schools would welcome the powers if they were accompanied by clear guidance.
"It is very difficult to search pupils because heads and teachers fear they will be accused of assault," he said. "That can be extremely frustrating if you are fairly certain that a child is in possession of a knife. We hope there will be guidelines to safeguard heads and teachers from those assault allegations."
Mr Dunford said that searches should always be carried out with at least two teachers present to reduce the risk of false accusations or violent resistance.
Other proposals in the Bill include raising the legal age for buying knives from 16 to 18 and making it illegal for under-18s to purchase replica guns.
Tougher sanctions will also be introduced for those who fire air-guns at other people.
The Bill follows the death in 2003 of Luke Walmsley, 14, who was fatally stabbed in a Lincolnshire school corridor.
The latest incident involving an air-gun in a school occurred this week at North Cumbria Technology College in Harraby, Carlisle.
Two boys, aged 12 and 13, were permanently excluded after a pupil was shot in the head during a lesson, suffering a minor injury.