Wales could follow the United States and England by giving headteachers and trained staff the power to search, without permission, pupils suspected of carrying knives and guns.
The Assembly government announced that it would start consultation on a change to the law in autumn 2009.
The new power, introduced in England last May by the former education secretary Alan Johnson, at first proved controversial with teaching unions.
They opposed the new powers, believing they could put heads at risk if they tackled armed pupils, and said it was a job best left to the police. They also said the move could increase costs of scanners and security staff.
But Gareth Jones, secretary of the Association of School and College Leaders Cymru, said this week his union had changed its mind.
"There were concerns last year when new powers were introduced in England," he said. "But those worries appear not to have been founded and we will not be opposing the new law at consultation.
"We are keen it is extended to Wales as soon as possible."
If approved, the new power, under Section 42 of the 2006 Violent Crime Reduction Act, would mean a head could personally search a pupil, a power currently held only by police officers.
But some teachers believe the move would mean the emergence of "fortress schools" in Wales at a time when they need to be open to local communities.
Iwan Guy, acting director of the NAHT Cymru, said: "We will have to consult members but I don't think many heads would want this power. I wouldn't want to tackle a pupil suspected of having a weapon."
Schools and police already have some powers when they suspect a weapon is on school premises.
Staff can search a pupil's desk or locker without the pupil's consent, along with a pupil's bag or jacket with consent. They can also ask police to do a personal search.
Police can also search a school unannounced without the head's consent if they suspect dangerous weapons are on the premises.
But Mr Jones said one area of the 2006 Act, section 100, on exclusions, was troubling heads more. According to Mr Jones, The Act says that schools excluding pupils must seek alternative provision within six days.
"If this happens, this will have to be funded by the Assembly government," said the former head.
New information obtained under the Freedom of Information Act recently revealed there is a small growth in reported incidents of dangerous weapon carrying in Wales's schools, including knives and air guns.
The information, provided by local authorities, indicates that under-15s are mostly responsible with a minority at primary level.
An Assembly government spokesperson said: "Heads in Wales need as many options as possible to make their school community feel safe and secure. However, this extra power would not be a duty."
Leader, page 28.