Teachers are often too scared to report incidents of violence or abuse in the classroom, according to a new report from a leading teachers' union.

The NASUWT said that in a single 10 day period, one teacher received a death threat while another was stabbed three times in the neck with a compass.

Neither incident was reported to the local education authority and no disciplinary or criminal action was taken, the union said.

Conducted in four education authorities in the North West in January, the study found 838 cases of verbal abuse and 126 of physical abuse, 62 of which were sexual and mostly directed towards women.

With ministers struggling to get on top of low retention rates among schoold staff, union general secretary Eamonn O'Kane said he believes these experiences are replicated throughout the country.

"Our survey paints a depressing picture of behaviour that goes way beyond the normal badinage of the classroom," he said.

"The sort of language employed can be deeply degrading, particularly to female teachers."

O'Kane believes some teachers fail to report incidents for fear of being labelled as "weak" by their colleagues.

The Conservative education spokesman extrapolated the figures to conclude that throughout the country teachers are physically attacked in schools more than 200,000 times a year

"These figures confirm a dark picture of the state of discipline in our schools," Damian Green said.