Experienced teachers from Commonwealth countries are being exploited and underpaid, according to academics.
A study published this week says that teachers, who often have more than 10 years' experience, are made to feel inferior because of the UK's outdated approach to overseas-trained staff.
Under current rules, teachers from EU states, even those with a relatively poor command of English, automatically get qualified teacher status (QTS) on entry to the UK. But staff from other countries, including Australia, New Zealand and South Africa, are paid around pound;5,000 less until they undergo a thorough assessment programme to gain QTS.
Overseas teachers can work in the UK for up to four years without the qualification. Training for the QTS assessment, which tests professional values, subject knowledge and classroom management, can take up to a year to complete.
Academics said the QTS programme was being shunned by most overseas teachers who considered it time-consuming, onerous and demeaning. Some said that had not known that they needed the extra qualification before they arrived in the UK - and almost two-thirds said they would not be attempting it.
The study by Manchester university and recruitment analyst John Howson, of Education Data Surveys is the latest in a series of snapshot surveys criticising the treatment of overseas teachers in UK schools.
It was commissioned by the NASUWT, the second biggest teaching union. Chris Keates, general secretary, said teachers from foreign countries were being exploited for profit.
"Within a global knowledge economy, the international movement of teachers should be a realistic proposition," she said.
"However, the education, cultural and economic benefits which might arise from this are unlikely to be realised where such teachers face negative experiences, discrimination, alienation and abuse in the countries where they seek to teach."
More than two-thirds of the 136 teachers who responded to the NASUWT study had four or more years' classroom experience.
Researchers also found almost three-quarters of the 195 headteachers surveyed believed overseas teachers had just as much subject knowledge as their British peers and 65 per cent were just as competent in front of a class.
In 2003, the Home Office granted 5,281 working visas to teachers from Commonwealth countries. These included 1,538 South Africans, 1,318 from Australia and 667 New Zealanders.
The study recommended that teachers, who have to be employed by a school before they can start working towards QTS, should be able to work towards it independently. It also said trained teachers with considerable experience should be fast-tracked through the course and more consideration should be given to their overseas teaching qualifications.
The recruitment of overseas trained teachers can be obtained from the NASUWT by emailing email@example.com