One teacher in 10 in Finland was subjected to violence at work last year - and more staff are doing self-defence courses to protect themselves.

Figures from the Finnish education trade union, the OAJ, show there were more than 1,000 violent incidents in schools last year - results that dent the nation’s reputation as an international leader in education policy.

Between 100 and 150 resulted in staff taking sick leave of between one and two months, and nearly all the instigators are pupils, says OAJ researcher Vesa Ilves.

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She said: “I would describe situations of violence mainly as those where a raging child is restrained to prevent self-harm or to protect others. In such situations, the principal or the director of the daycare has to also assist or intervene.”

Most cases - 650 - were in secondary schools, with 400 in primary establishments. The figures are on the rise - 9 per cent of teachers subjected to violence last year had to take sick leave, compared to five per cent in 2017.

Ms Ilves said: “Longer sick leaves have been observed in comprehensives. Perhaps, the situations turn more serious as the students are stronger.

“If the aggressive student is not provided with sufficient support and remains in the same classroom, the teacher may suffer from mental strain after returning from sick leave.”

She suggested integration of special needs pupils into the classroom may increase exposure to violence if support measures are not provided.

The figures might be seen as surprising, or counter-intuitive. Not only has Finland often finished highly in global education rankings, it has also a reputation as a society where teachers are highly respected and listened to.

But Finnish teachers now have to take steps to protect themselves. Finnish self-defence instructor Janne Ahonen said: “Educational institutions have been increasingly organising self-defence and threat training for school teachers and directors.

“We practise safely approaching, holding back and removing an aggressive student from the classroom.”

Excessive force is forbidden, with teachers taught to use legal, gentle means of resolving conflicts.