THE president of Scotland’s biggest teaching union has warned a strike in schools is increasingly likely due to a dramatic slump in staff pay.

Nicola Fisher of the Educational Institute of Scotland issued the stark warning after the Scottish Government's budget was passed at Holyrood, claiming teachers' pay levels have plummeted by 20 per cent in the last decade.

The EIS leader makes her highly-charged intervention in the forthcoming edition of the Scottish Left Review, maintaining extreme workloads are having a "devastating" impact on the physical and mental health of teachers.

Staff, she writes, experienced constant shake-ups in education that had been "enormously unsettling" leaving teachers "stressed and exhausted.

"They work far longer than their contractual hours but still never get to the end of the work. The effect on teachers’ mental and physical health is devastating."

Fisher, a primary school teacher, adds: "For the last 10 years we have experienced almost constant change. That, in itself, is a huge workload issue for teachers and is also enormously unsettling."

The EIS has called for a 10 per cent pay rise for all teachers.

However, Fisher claims the pay of teachers did not reflect upheavals in schools and that the EIS felt it was being forced into striking – and that these strikes could take place despite restrictions on industrial action passed by Westminster.

Fisher says: “The EIS could be looking at strike action over pay this year.

“It is very clear that the Tory Trade Union Act is an overt attempt to prevent unions striking to defend their members.

“However, with good campaigning and the support of members, we can overcome the barriers which the Act tries to put in our way."

She goes on: “Teachers’ pay has declined by 20 per cent in real terms over the past decade, or by up to 24 per cent when you factor in changes to pension contributions and national insurance.

"In common with most other workers in the UK, teachers have been made to pay the price for a financial crisis which we did not create.”

Fisher also describes teachers' workload as "the iceberg of the education system. Observers such as politicians think they understand about workload because they can see the tip of that iceberg, but they have little concept of the scale of what lurks below the surface.

"This is largely because the problem is not just the workload in and of itself, but also its impact and implications.

"Research confirms that the health and wellbeing of our members is really suffering."

In response, a Scottish Government spokeswoman said: "It should be noted this Government was the first in the UK to commit to lift the 1 per cent public sector pay cap, and the teachers’ pay deal for 2017-18 reflects this commitment."