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.
The new guidance will be issued "shortly" but a specific date has not been announced.
Ms Keegan - who will address her party's conference in Manchester on Monday afternoon - will say mobile phones are a distraction and are often used for bullying.
The new guidelines will be designed to allow pupils to bring their phones to school so they can be used on the journeys there and back but will not be allowed to use them during the school day.
Introducing national restrictions on phone usage in schools is an idea that has been touted before, including by Schools minister Nick Gibb in 2019.
Former Education Secretary Gavin Williamson also said he favoured a ban in 2021, saying "mobile phones should not be used or seen during the school day".
