A Wiltshire head teacher has defended locking toilets during lesson time.
Anita Ellis said letting pupils go to the toilet within minutes of a lesson starting can be "massively disruptive".
Royal Wootton Bassett Academy is one of many schools across the UK following to practice as they also see a rise in vandalism and vaping during lessons.
But a charity has called for the government to look again at how schools decide rules around pupils' access to toilets.
Speaking to BBC Radio Wiltshire, Ms Ellis said: "If you can imagine a class of 30, every student after a few minutes asks to go to the toilet then learning is stagnating.
"The learning does stop and so it is massively disruptive."
She said the policy was about "protecting the students".
