Exam board Edexcel is at the centre of a leak relating to an A-level maths exam sat by pupils on Friday.
Pearson, the firm which operates the board, said it was "investigating" after blacked out images of two exam questions from Edexcel's maths paper 3 appeared on Twitter last night.
However, students who have seen the documents claim the entire paper was up for sale and images of several questions have been posted online.
Tweets accompanying the images offered the whole paper for sale for £70.
Scores have now signed a petition on Change.org titled 'Justice for leaked Edexcel A level Maths'.
This is not the first complaint this week regarding Edexcel, the board was also the subject of two petitions days earlier complaining about the difficulty of other A-level maths papers.
The leak prompted a backlash on Twitter with students quick to voice their anger.
Molly Hill said: ''@PearsonEdexcel, you cannot do anything but cancel these papers when there are students with the WHOLEPAPERS on their phones#edexcelmaths.''
Scarlet@scarlybt tweeted: ''Honestly wont be sleeping until @PearsonEdexcel decide to tell us what’s being done about this maths leak...''
In a statement, Pearson said: “We are aware that an individual circulated blacked out images of two exam questions on social media ahead of today’s A-level maths exam.
"We are investigating the source of this. 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 re-sat.”
Edexcel A-level maths papers were also leaked in 2017 and 2018.
In April this year, it was reported police had referred a file of evidence to the Crown Prosecution Service, which will consider bringing criminal charges.
The file dates back to a leak in 2017 when Edexcel was forced to issue replacement questions at the last minute to a limited number of exam centres after reports that some students had access to content in advance.
The following year, another maths A-level paper was reported to have been leaked online a day before thousands of candidates were due to sit the exam.
Pearson said an investigation into the 2018 leak was continuing but it hoped police would send a second file to the CPS shortly.