Teachers are "on their knees" with low pay and high workloads taking a toll on mental, physical and emotional health, a union has warned.

Nicola Fisher, president of Scotland's largest teaching union the EIS, said public sector workers were "paying more, working longer and getting less".

Speaking at a fringe event at the SNP's conference in Glasgow alongside Education Secretary John Swinney, she said teacher's pay had fallen in real terms by about 16 per cent with changes to pensions, tax and national insurance leaving them worse off to the tune of hundreds of pounds per month.

Ms Fisher added: "For people actually to be coming out with less in their hand at the end of their working month, quite honestly is a disgrace and of course that has been the result of ideological decisions taken by the Tory party at Westminster.

"We then have a scenario where teachers are opting to work in other countries or in other careers which pay better and quite honestly I don't think we can blame them.

"Unfortunately we are seeing a lot of our young graduates completing their probation year and then going to work abroad."

Ms Fisher said workload was the "iceberg" of the education system, adding: "Unless you are experiencing it day in, day out you cannot hope to grasp the full horror of what lurks beneath the surface."

She encouraged teachers to push back against workload pressures, saying a failure to do so would be "propping up a broken system".

Citing research showing 40 per cent of Scottish teachers were thinking of leaving the profession in the next two years, she said: "Much of that has come as a result of deliberate Tory policies on cuts to the public sector.

"But whatever the source, our teachers are on their knees and if we want to close the attainment gap and we want a first class education system we have to help these people, whose mental health is suffering, whose physical and emotional health is suffering and whose family life and personal life is suffering."

She added: "If you look at what we do in this country, we underpay teachers, we overwork them, we tell them they are part of a failing system, there is constant change, extending the presumption of mainstreaming - we don't provide enough resources to support what's going on in our schools and then we are surprised that 40 per cent want to leave.

"I'm actually surprised it's not higher."

But Ms Fisher warned against fast-track schemes such as Teach First, describing them as "the wrong fix" that would create "churn" in the system rather then solve the problem.

Responding to a suggestion from the floor, Mr Swinney said he did not think a longevity bonus was the right approach to solve the issue of teacher retention.

He acknowledged "pay is an issue" but highlighted Finance Secretary Derek Mackay's comments to the conference on public sector pay, in which he warned that the government's ability to give staff a wage rise could still be ''constrained'' by UK Chancellor Philip Hammond.

On the attractiveness of the profession, the Education Secretary hit out at the media, saying: "I despair about some of the nonsense I see written in newspapers by ill-informed commentators which lacks substance and basis".

He said that under the government, clarity in the education system was "bedding in" while on workload he was working to "empower the teaching profession to do what's necessary for the learners journey".