Supply teachers are the victims of “profoundly exploitative employment practices,” a teaching union has claimed.

A survey of almost 1,000 supply teachers by the NASUWT teaching union found 68 per cent had not been made aware of rules that entitle them to the same pay and conditions as permanent teachers after 12 weeks in one workplace.

And 11 per cent of respondents said they had been asked to waive their rights to this entitlement, which is set out in the Agency Workers’ Directive.

Sixty five per cent of respondents said they were not paid at a level that recognized their experience and 91 per cent said they were not always given appropriate information to support them the first time they entered a school.

And despite teacher shortages, forty three per cent said the number of days per year that they could secure work had fallen in the past year.

Almost 70 per cent of the teachers that left contracted roles for supply work did so in a bid to achieve a better work-life balance, the survey found.

One teacher responding to the survey said: “In my current assignment doing maternity cover I am expected to fulfil a full teaching role but I am only paid a daily rate, and not paid during the holidays.

“Over Christmas I did up to 70 hours of marking and preparation without being paid.”

Another said they regularly felt that they were “thrown in at the deep end”.

The union is calling for “urgent action” to regulate all supply agencies, and for national standards for the employment of supply teachers.

A motion to be discussed at its annual conference in Birmingham today says: “Many supply teachers continue to be the victims of profoundly exploitative employment practices by some employment agencies.”

Some agencies “deny them teachers’ national pay and conditions; refuse to offer membership of the Teachers’ Pension Scheme; fail to offer appropriate continuing professional development and fail to offer minimum levels of work, effectively promoting zero-hours contracts,” it says.

NASUWT general secretary, Chris Keates, said: “Supply teaching is a tough job, made even harder by the exploitation and poor employment practices supply teachers often face.

“Many supply teachers report that opting for supply work is their final attempt to hold on to the profession which they love, yet they find themselves being deprived of the pay and working conditions to which they should be entitled.”

On Saturday the National Union of Teachers conference in Brighton passed a motion calling for a central supply teachers register to be set up and more training for supply teachers.

NUT general secretary, Christine Blower, said: “Supply teachers provide a vital service in our schools. There is, however, a significant issue with pay and conditions for this group of teachers. Many are paid well below those on permanent contracts.

"The agencies, however, continue to drain millions of pounds from education funding. The rip-off of agencies which profit at the expense of decent pay for supply teachers has to stop."

A Department for Education spokeswoman said: “Supply teachers form a valued part of the teaching profession. The flexibility they offer is important in allowing schools to meet their teaching needs and we trust schools to use them appropriately. There are clear laws in place to ensure supply agencies treat their staff fairly.”

*TES Global, the parent company of TES, owns two supply agencies, Vision for Education and Smart Teachers.