Internet game operators in China must deter young people from playing more than three hours a day to combat online addiction, according to a circular issued by eight government departments on Monday.

The number of Internet users in China reached 123 million in mid-2006, the Xinhua news agency said on Monday, citing official statistics. About 15 percent -- or 18 million -- are under the age of 18.

Game companies must develop a system that cancels half a minor's earned gaming credits if they remain online for more than three hours a day. If the young person plays for more than five hours a day all of their credits will be taken away.

Online gamers will also be required to register using their real names and identity card numbers which will indicate if they are under the age of 18.

Companies must develop an anti-addiction system by June 15, fully test it by July 15 and implement it thereafter, according to the circular.

It was issued by eight government departments, including the State Press and Publication Administration, the Ministry of Education and the Ministry of Public Security.