Bangladeshi exam cheats used mobile phones disguised as watches to get round bans on handsets during tests, in a scam that has been going on for three years.
People sitting university entrance exams and tests for job interviews have been renting out the devices, allowing them to receive answers while the examinations were underway.
Ten people arrested for running the scheme have admitted importing tailor-made devices from China, and bribing teachers to receive copies of tests in advance.