Secondary school chiefs have banned pupils from going to the toilet during lessons – unless they have a note form their GP about a 'relevant medical condition'.
Westlands School and Sittingbourne Community College in Sittingbourne, Kent, even lock the toilet doors during class times so kids can't relieve themselves without permission.
Simon Cox, the head of Westlands School, said the only toilets open to children during lessons were at the nurse's office.
He added: "During lessons, when teachers are in classrooms, safeguarding protocols would suggest that it is not common sense to allow pupils to have access to toilet areas which are not supervised.
"We encourage pupils to use our extensive toilet facilities at break time and lunchtime, but the school provides an alternative facility during lessons, which is supervised by our support team."
Sittingbourne Community College head Fiona Trigwell said: "The policy of the school is children don't go to the toilet during lesson hours."
The drastic measures have provoked anger amongst parents.
One father of a 12-year-old boy said: "My son came home and told me that all the school toilets were locked when they were in their lessons.
"He said that one pupil asked to go, saying they were desperate and they were told they could only go during break time.
"The simple fact is that children are embarrassed to ask in front of their friends, so the school will end up dealing with a lot of wee on the floor if they don't change the policy."
Clare Stevens said her stepson Kieran was a pupil at the Westlands School and that he had been refused to be excused from class to go to the toilet.
She said her son was told he must go and see the nurse first, who would then decide on whether he could use the loo.
She told the Sittingbourne News: "The nurse's office is a 10 minute walk to the other side of the building, and all the toilets are locked on the way there.
"When he got there the nurse questioned him about why he had to go."
Mum Sam Bright, whose daughter is in Year 8, said: "She was absolutely bursting the other week and she was told that she couldn't go and to sit back down unless she had a medical note."
A spokeswoman for children's charity ERIC (Education and Resources for Improving Childhood Continence), which campaigns on the slogan 'Every Child Has The Right To Go', said the policy was 'totally wrong'.
Rhia Weston, of ERIC, said: "It is extremely important that children are allowed to go to the toilet when they need to, otherwise they can develop problems with their health and wellbeing.
"Preventing them from going by locking toilets or having a school policy of no toilet breaks is the completely wrong approach.
"What schools often don't realise is that this kind of policy can affect children's school performance as well because of the impact that holding on or not drinking enough water can have on concentration and energy levels.
"Children who do not drink enough water at school because they want to avoid using the toilet can also suffer from headaches.
"This is an issue that affects all pupils, not just those with continence problems, so schools need to take it seriously."