A cheating probe has been launched after images of an A-level maths exam were circulated online.
Images of a paper set by exam body Edexcel appeared on the web shortly before the maths test was sat by students on Friday.
Pearson, Edexcel’s parent company, said it had taken action to identify the source of the leak.
“Having visited a small group of centres within scope of the investigation, we have identified one centre in serious breach of correct practice,” the firm said.
“We are determined to identify the individual involved, and hold them to account.”
Pearson said it was aware that images of the paper “were circulated in a very limited way shortly before the exam”.
It added: “All students should be reassured we have well-established processes in place to ensure no-one will be advantaged or disadvantaged, and this paper will not have to be resat.”
The incident comes after similar leaks in 2017 and 2018 when A-level maths papers were put up online ahead of the tests.
The leaks were probed by the police and evidence was passed to the Crown Prosecution Service for consideration over whether criminal charges should be brought.
Earlier this year, Pearson said it would be trialling a scheme where microchips were placed in exam packs to track the date, time and location of the bundles.