Some Chinese universities are to block mobile phone signals at exam halls in a high-tech bid to stop cheating, Xinhua news agency said on Thursday, warning that the practice may not be good for the students' health.

Some 9.5 million students sit college entrance exams next week with vacancies for only 2.6 million undergraduates, Xinhua said, underlining the highly competitive nature of education in China.

Last year, approximately 1,700 students across the country were disciplined for cheating.

"Several police departments last year probed nearly 30 cases involving more than 30 suspects who were caught using hidden telecommunication equipment to cheat on the exams," Xinhua said.

"Colleges and universities in Shandong, Heilongjiang and Liaoning provinces started to shield mobile phone signals at exam halls last year, and several other schools are planning the same move this year, even though some experts claim the scrambling devices may have unhealthy side effects."

All the student-hopefuls will be required to sign a paper promising not to cheat and the government will compile a database as of this year that will contain "credibility records" of exam takers.

"China's police will also be on guard to ensure smooth operation of the exams," Xinhua said.