Exam board Edexcel has launched an investigation into how part of an A-level maths paper was leaked online.
Blacked out images of two questions were shared on social media on Thursday afternoon.
Pearson, which runs Edexcel, said the images were circulated “in a very limited way” shortly before Friday’s Maths Paper 3 exam.
It reassured students no-one would be advantaged or disadvantaged and they would not have to re-sit the paper.
The questions were first posted from a Twitter account in a since deleted post, where the user urged students to “get in touch”, offering the whole paper for £70.
Pearson said it had taken action to identify the source of the breach and was “determined to identify the individual involved”.
After visiting a small group of centres, the company said it had identified one “in serious breach of correct practice”.
It is the third year in a row that A-level maths questions from an Edexcel paper have been leaked.