"A substitute can earn as much as 200,000 yuan ($31,700) a month from students to do their work for the arts exam," according to a student who did not want to be named.

Haizhu district government launched a special investigation into the studios on Thursday, but many were found to be empty.

Xiaozhou village has many studios, but only 16 of them have been granted a license to operate, authorities said.

He Liping, a professor from the school of sociology and anthropology with Sun Yat-sen University in Guangzhou, said cheating had been investigated in many examinations, including the national entrance examinations for universities and colleges, in the province in recent years.

"There are loopholes in the running of the examinations," he said on Thursday.

He urged relevant departments to strictly implement regulations to close the loopholes.

Chen Yingwei, a senior high student in Guangzhou's Yuexiu district, said cheating is shameful conduct and unfair to honest students.

"Relevant departments should introduce stiff and effective measures to prevent cheating to ensure a fair environment for all students in examinations," he said.

A total of 157 Chinese universities and colleges arranged arts examinations in nine test centers in Guangdong this year.

More than 180,000 students have participated in the examinations from Jan 30 to Feb 22.

Zhang Yiren contributed to this story.