Police were called when a protest erupted at a school in North Yorkshire after students were limited to two toilet breaks a day.
Officers were forced to be called in after up to 40 students took to the playing fields on Friday morning protesting the controversial new rule at Bedale High School.
Parents have criticised the school after being informed the 580 pupils were only allowed a bathroom break between 11.05am and 11.25am, and 12.25pm and 12.45pm.
The decision was criticised as "breaching human rights", but the 11-16 comprehensive school maintains the toilets are accessible on request and to those who held a 'medical card'.
Parents first learned of the new policy by a letter in February, which ITV reported as saying: "There is no access to the main building (where the toilets are located) after 12.45pm."
Lunch finishes at 1.10pm, adding to the outrage.
One parent, who posted anonymously on Facebook, said: “I believe that this is humiliating and undignified and is a breach of human rights to be denied access to toilets at any other time unless you have a medical need, and totally ridiculous to say that you cannot go to the toilet after you have had lunch.
“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 saying I felt this was a breach of human rights and she wrote back saying that those with medical issues would need to get a note from the doctor.
“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 just degrading.”
And Pupil Madelaine Anderson agreed, writing: "I find this unfair on everyone not only girls but also boys, not everyone needs to have a 'medical note' to be allowed to use the toilet."
But a notice posted on Bedale High's website defended the move, saying the new behavioural code was part of an overall action plan.
They said: “The code also includes tighter rules on uniform and on reducing the numbers of students outside of classrooms during lesson time.
"As part of this the school has reminded students that toilets are freely accessible during specific periods at lunchtime and break time but that students who need the toilet during lessons, or need access for medical reasons, will always be given access on request. Toilets are therefore accessible at all times."
A spokesman for North Yorkshire police confirmed they were called to a protest at the school but advised staff it was not a police matter.