Head teachers in England will be told to ban pupils from using mobile phones during the entire school day under new government guidance.
The Department for Education wants children to be barred from using devices on breaks as well as in class.
Education Secretary Gillian Keegan will announce the plans at the Conservative Party conference on Monday.
The government already encourages head teachers to limit phone usage and many schools have restrictions in place.
But government sources say they are confident expanding the guidance will make a difference in reducing the use of phones during the school day.