Almost 300 school and college students were disqualified from exams in England last summer for malpractice involving mobile phones, figures show.
Cheating is taken seriously, exam boards warn
Of the 287 banned, all but three were sitting GCSEs, A-levels or vocational qualifications set by AQA, the UK's biggest exam board.
The overall number of subject bans for mobile possession and use represented a 15.7% rise on 2003.
An AQA spokeswoman said: "The figures show that cheating is taken seriously."
Some students had attempted to receive answers via text messaging - particularly in more factual subjects such as maths and science.
Others had inadvertently taken handsets into the exam hall.
Last summer, AQA banned 248 candidates from GCSE subjects for mobile phone-related malpractice and 36 from A-levels - out of a total of 476 cases it investigated.
OCR, another board, disqualified two exam candidates out of 282 it checked, and Edexcel just one out of 255 about whom it had concerns.
Those two boards were more likely to have imposed the lesser punishments of docking marks or disqualifying students from sections of exams.
The AQA - which deals with more candidates than the other boards put together - did this 19 times, and issued 136 warnings.
Its spokeswoman said all boards had the same, agreed, anti-cheating policies and followed the same procedures.
OCR spokesman Bene't Steinberg said some children brought mobile phones into exams by mistake, as they were so used to having them on their person.
He added: "Most cheating is very obvious and we have got expert markers, who can spot when people are cheating and will do so."
Exam boards do not have staff present in exam halls. Schools appoint invigilators to maintain order.
The figures are those presented by the boards to the English exams watchdog, the Qualifications and Curriculum Authority.
A QCA spokesman said: "The simple message is 'Don't cheat'. If students cheat, they will be punished."
A spokesman for the Scottish Qualifications Authority said it had no figures because it did not have a problem with cheating.
Candidates were given very specific instructions about what was not acceptable.
"That's something we nipped in the bud a long time ago," he said.