BEIJING -- China is investigating the death of a teenager who was allegedly beaten to death in a camp designed to treat Internet addiction, state media said.

Deng Senshan, 15, died Sunday, less than a day after his parents sent him to the camp in southern Guangxi province, Xinhua News Agency reported.

The case has led medical experts to call for laws regulating centers that treat obsessive Web surfing. Concern over such behavior is so widespread in China, and demand for rehabilitation is so great, that some camps now advertise on television, the report said.

Deng was found vomiting and was taken to a clinic where he died. Fellow students said a teacher beat him, Xinhua reported.

The report quoted the local government as saying several marks were found on the boy's body. It said four trainers from the Qihang Salvation Training Camp in Nanning city have been detained.

Police and government authorities in Nanning could not be reached for comment Thursday.

Controversy over the methods used in addiction-treatment camps led the Ministry of Health to issue a notice last month banning the use of electric shock therapy on Internet addicts at one hospital in eastern China.

Tao Ran, director of the country's first Internet addiction treatment clinic under a military hospital in Beijing, told The Associated Press that such deaths are bound to happen because few camps employ scientific methods, with most opting for crude military-style discipline.

Tao said 40% of those addicted to the Internet suffer from attention deficit hyperactivity disorder, and find it difficult to obey orders at training camps.

"They are only one-fourth or one-fifth as efficient in their academic life," he said. "Once you put these kids to the training camps or schools, they are bound to have problems with the teachers, because ... they can't be still, while the training is all about keeping still."

Internet addiction is a big problem in China because 200 million Internet users are between the ages of 15 and 35 and many lack self-control, Tao said. Students at high school and college also face enormous pressure from parents to succeed academically.

Tao's clinic has treated about 5,000 Internet addicts since 2004.

Xinhua said the numbers of treatment facilities and addicts treated have soared in the past few years in major cities.

China's National People's Congress has estimated that 10% of China's Internet users under age 18 are addicted. Chinese psychologists say symptoms include being online more than six hours a day — playing games or looking at pornography rather than working or studying — and getting angry when unable to get online.

Deng's father told Xinhua his son spent all his time on the Internet. He said he sent his son to the camp after seeing an advertisement on television.