The number of overseas teachers working in the UK will be cut under new hard-line immigration laws, recruitment analysts have warned.
In a little-publicised addition to reforms unveiled by the Government last week, teachers from Commonwealth countries will only be permitted to work in the UK for one year instead of two.
And the Home Office has almost quadrupled the cost of applying for extended stays.
Thousands of teachers from countries including Australia, New Zealand, South Africa and Canada enter the country every year under the Commonwealth holiday working visa scheme.
It is one of the most popular routes into the country for overseas teachers. But the legal changes could deter hundreds from applying, leading to a shortage of supply teachers in areas with high vacancies, like London and the South-east.
Midge Lewry, director of supply agency TeachLondon, said: "Teachers want to stay for the full two years - there is so much they want to see and do in England, Ireland and Scotland.
"Any reduction in the amount of time teachers can work in this country will have quite a serious effect and could turn some people off coming."
In 2003, the Home Office granted 5,281 working visas to teachers from Commonwealth countries. It included 1,538 South Africans, 1,318 from Australia and 667 New Zealanders.
The working holiday visa, only open to under-30s, is one of three routes teachers can use to enter the UK and is the most popular. An estimated two-thirds of all Commonwealth teachers are believed to use it.
Under the new restrictions, visa holders can remain in the country for two years but are permitted to work only for 12 months.
Teachers deemed to be highly-skilled can apply to extend their full-time working rights for more than a year, but the Home Office has announced that applications for longer stays will now cost pound;500, instead of the previous pound;121 fee.
Recruitment expert John Howson, visiting professor at Oxford Brookes university, said: "It will have a significant effect in areas with the most acute teacher shortages. They are an important reservoir when not many teachers in this country are looking for jobs."
But Alan Smithers, from Buckingham university, said the change would focus the minds of schools on finding lasting solutions to teaching vacancies.
"We have been able to patch over the cracks with teachers from the Commonwealth, but that is not solving teacher-recruitment problems in the long term," he said.
Even with permission for an extended stay, teachers can only work in the UK for a maximum of four years without qualified teacher status.
The General Teaching Council for England is currently cracking down on teachers working beyond the deadline without QTS.
Mike Kaye, chief executive of Tradewind Recruitment, said up to 800 people from Commonwealth countries are attracted to the UK every year through his agency, with more than two-thirds entering on the two-year working holiday visa.
"They are attracted to the fact that they can work here for two years," he said. "In countries like Australia and New Zealand it has become a right of passage for generations. One year may not be enough time for many of them."