Two "ghost writers" who tried to write Monday's grade 12 mathematics paper for two other candidates have been arrested.

The two were caught at the Shaka's Kraal Adult Basic Education and Training Learning Centre in KwaDukuza.

Education department spokesperson Christi Naude said that an invigilator was verifying identity documents when she noticed something was amiss.

"An official scrutinised the identity documents and found that the documents of the ghost writers did not match those of the people who were supposed to be writing. The police were then called, and the two were arrested," she said.

Naude said they would trace the candidates who were supposed to write the exam, and they would have to account for the incident.

"According to procedure they will continue writing the rest of the matric exams that they have registered for. But their results will be held until they appear before an irregularities committee. They will then be given a chance to put their case forward. Depending on the outcome, they could be barred from writing matric exams for a certain period, and they may also be charged criminally," she said.

"It's a lesson for other people. We are serious about cheating and it will have serious implications. We are checking everyone's particulars. It is crucial that the exams are credible. This is the first irregularity we have picked up since the exams started," said Naude.

Police Inspector Michael Read said the pair had been charged with fraud and would probably appear in the Verulam magistrate's court on Tuesday.