AT least 24,000 supply teachers in Britain could benefit from European Union reforms aimed at improving the pay and conditions of temporary staff.
Recruitment agencies could be forced to put them on the same rates as permanent teachers - and provide pensions entitlement and holiday pay.
The directive, reportedly due to be published next month, is designed to give up to 6.5 million temporary workers across Europe the right to the same pay and conditions as long-term staff in comparable jobs.
Temporary staff recruited by councils are paid daily rates on the same scale as permanent employees but there are no such rules for the 24,000 teachers working for employment agencies.
Some supply teachers are now on a better daily wage than their long-term colleagues but unions have long argued that, for many, rates are worse and include neither pensions nor holiday pay.
Graham Clayton, the senior solicitor at the National Union of Teachers, said: "A European directive to this effect would be very welcome for teachers and the profession as a whole.
"It could result in the kind of conditions of employment for supply teachers which we have been campaigning for for the past 10 years."
But Diane Sinclair of the Chartered Institute of Personnel and Development said that the move would damage the flexibility of businesses to set pay and conditions for agency workers.
The move came as a leading agency warned that schools could lose the services of 2,000 supply teachers under changes to the system for criminal records checks.
Select Education said the introduction of the Criminal Records Bureau on March 1 would lead to a six-week delay in placing temporary staff. All police checks will have to be carried out before they are cleared to teach.
Meanwhile, TES enquiries have revealed that at least three supply agencies are making more than pound;3 million a year in profit, with directors receiving bonuses of anything from pound;22,000 to pound;616,000.
According to last available figures, Protocol Teachers (formerly Spring), made a profit of pound;8.7 million on a pound;34 million turnover; while Teaching Personnel made pound;3.6 million on a pound;14 million turnover, with directors each awarded an average of pound;37,000.
Timeplan, the agency at the centre of the Amy Gehring controversy, made pound;5 million on a turnover of pound;22 million, with its three directors awarded an average of pound;617,000.
The company with the largest recorded turnover was Select, at pound;62 million, although it could not provide its profit figures.