China's on-line gamers may soon find their favorite games come with an age rating to show whether they are suitable for children or for adults only.

In Beijing, more than 30 on-line game operators led by the Beijing Animation and Game Industry Alliance have agreed to make age recommendations for players.

Alliance secretary-general Liu Chungang said the system was voluntary and was designed to protect young players.

Liu Chungang said alliance members would be required to add age tags such as "For adults" or "Suitable for all ages" by March.

In Shanghai, about 30 online game operators, including Shanda, the second-largest online game operator, have joined the campaign. Tencent, the largest online game operator, so far has not responded to the initiative.

But Liu Shihui, an officer with Tencent's public relations department, told Xinhua the company had been studying a rating system and believed the core value of any rating hinged on whether operators would give real attention to protecting the healthy development of minors.

Liu Shihui said the company hoped the authorities would release guidelines at an early date in this regard to ensure a faster and healthier development of on-line gaming industry.

Liu Qiang, an officer in charge of the Internet culture with the Ministry of Culture (MOC), said the moves were enlightening and the ministry was considering extending it across the country. But Liu did not give specific date on a decision to promote it.

"We will assess the practice and draw from their experience," Liu Qiang said.

The number of online game players in China surged 33 percent to 66 million over the past year, said a report released at the annual conference of Chinese gaming industry on Jan. 20.

According to a separate report by the MOC released two days before the conference, almost one in six of these players was a minor.