Police have been called to Bedale High School where it is understood a student protest over a new school rule is taking place.
North Yorkshire Police have confirmed that two officers have attended an 'ongoing incident' at the school.
It is understood there are some 40 female students taking part in the protest.
A parent, who did not want to be named, said: "They have stopped the children going to the toilet - they can't go in lesson time which I suppose is understandable to an extent but they have also stopped them going for half of their lunch break.
"They can go between 12.25pm and 12.45pm and from then they can't go to the toilet at all and lunch finishes at about 1.10pm.
"My daughter had stayed behind in her class to do extra work and then went to the toilet at 12.45pm but staff wouldn't let her go.
"I wrote to the Head to say I felt it was a breach of human rights and she wrote back saying basically that's what they are doing, that was it and that those with medical issues would need to get a note from the doctor.
"Girls are having problems when it's the time of their month. It's appalling, the fact that if they have got medical issues they have got to show a pass, they are making them a target for bullies, it's not good.
"There seems to be an awful lot of support from other parents. I have already had a reply from the head but I have asked to speak to a governor."
Bedale High School have been approached for a comment.
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