The police and education authorities will collaborate on this matter, Tang said. Checks will be made on every examination paper and each examinee's identity.

Test proctors, or invigilators, will also be investigated to see if a chain of interest is at work.

With the country's increasing number of university graduates and the difficulties of securing employment, about 1.5 million students took the nationwide exam for postgraduate studies on Jan 15 and 16, a record high since 2001.

The ministry vowed to take harsher measures against cheating on the exam this year, arranging for 107,000 monitors to be present at the 46,000 examination venues around the country.

Electronic watches that had been specially adapted and wireless earphones were sold in Siping in the run-up to the postgraduate entrance exam, with answers provided within a one-kilometer radius of the examination venue, according to the CCTV report.

Devices used to cheat on exams are usually purchased over the Internet and the working group in Siping ruled out the possibility of someone in the city leaking information before the test was held, People's Daily reported.

Siping education officials suspended the grading of exam papers until the investigative team completes its work.

Despite heightened vigilance, 359 applicants committed violations during China's 2011 national civil service exam held in early December, the State Administration of Civil Service revealed over the weekend. Those caught cheating on the exam will be blacklisted and banned for life from applying for civil service jobs.