The pupils are told to remove wrist watches before making GCSE and A-level exams, to combat the scams.
In most cases, students are told to place the watches on the desk, but the assistants can demand they are left outside of the exam hall.
The new rule was introduced to prevent pupils from trying to pass smartwatches – which have long been prohibited – as normal ones.
Some universities have already imposed similar requirements.
The regulation was announced by the Joint Council for Qualifications (JCQ) in an online guide published last July, but it was the first time this week by Gloucestershire Live news site.
The rule is also intended to prevent the test-takers trying to smuggle in notes folded and placed in conditions of normal watch faces.Hidden earphones
Various watches are explicitly marketed as cheating devices can be found advertised online, including Amazon UK store.
Some of the works by pressing a button to replace a graphical representation of a dial with the loaded text, but others do not have the digital display and the playback of audio from a small built-in speaker, through a Bluetooth connection.
Different examination centres had already introduced ad hoc to look at the bans.
But the JCQ move means that most students of schools and exams in England, Wales and Northern Ireland are now interested.
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Even if some of the JCQ members of the award Scottish Highers, exams are not covered by the change.
A spokesman for the organisation told the BBC that he had posted a video earlier this week to provide pupils with more information.