Chinese doctors released the country's first diagnostic definition of Internet addiction over the weekend, amid efforts to address an increasing number of psychological problems that reportedly result from Internet overuse.

Tao Ran, a medical expert at Beijing's Military General Hospital, where the definition was developed, said it was also the first time for China to officially designate hospital psychiatric units to treat such cases.

Symptoms of addiction included yearning to get back online, mental or physical distress, irritation and difficulty concentrating or sleeping.

The definition, based on a study of more than 1,300 problematic computer users, classifies as addicts those who spend at least six hours online a day and have shown at least one symptom in the past three months.

"Eighty percent of addicts can be cured with treatment, which usually lasts about three months," said Tao. He did not describe the treatment, however.

According to the China Youth Association for Network Development, Internet-addicted youths are more likely suffer frustration in interpersonal relations than their peers.

Those aged 18 to 30 account for nearly half of the online population in China, which has been estimated at 210 million as of2007 by the China Internet Network Information Center.

About 10 percent of young users suffer Internet addiction, an earlier survey revealed, and about 70 percent are male.