Authorities in central China have halted an exam scam, seizing more than a dozen suspects and penalizing 14 students who paid for their services.

The suspects allegedly offered students answers to the national college entrance exam between June 7 and 9 via radio transmission methods, including having receivers hidden in clients' mouths, Xinhua News Agency reported on Monday.

Suspicious radio signals were detected on June 7 in a routine patrol around exam spots in Xinhua County of Loudi City, Hunan Province, by government vehicles with wireless signal detectors, which triggered a county-wide investigation by police and education authorities.

A task force set up over the issue caught four suspects the next day and seized high-tech devices.

Other suspects were apprehended outside the county.

Police said the two ringleaders, Liu Wu and Liu Ping, carried out the plan at the end of last year and set up a group with 16 others they recruited.

They bought special devices in Beijing and Wuhan, capital of neighboring Hubei Province, and contacted students before this year's exam.

The going price for exam leaks was between 4,000 yuan (US$585) and 6,000 yuan for varying subjects. Students were then trained on how to use the devices.

Five suspects who took part in the exams left 30 minutes before the end of each subject carrying questions.

Liu and others waiting outside took photos of the questions and sent them electronically to their accomplices in a local hotel.

These people answered the questions and sent them on to the student buyers.

The Hunan provincial government tightened exam security this year and adopted many high-tech methods, including jammers and video-surveillance systems.

At almost the same time, prosecutors in Fuyu County of Songyuan City in northeast China's Jilin Province have ratified the arrest of two teachers who sold devices to students to help them cheat in the university entrance exams.

Two teachers, Liu Yanhua and He Shujie, and their alleged accomplice, Yang Chun, were caught by police on June 5 while testing the devices.

(Shanghai Daily August 4, 2009)