China’s leading Internet companies are reported to have reached “a common agreement” to give the government greater control of information on the Internet, and social media in particular.

The Chinese government, according to Reuters, has received support from ten of the country’s top technology firms — including e-commerce firm Alibaba, search giant Baidu, and dominant microblogging platform owner Sina — as it looks to introduce new censorship measures to “stop the spread of harmful information” over the Internet.

Top executives from the companies met with state officials during a three day private conference which, upon ending this weekend, saw Wang Chen, director of the State Council Information Office, confirm a deal to “conscientiously safeguard the broadcasting of positive messages online”. Going into more detail, Chen said it will “curb the spread of rumours online, online pornography, Internet fraud and the illegal spread of harmful information on the Internet.”

The ambiguity of a number of those phrases — including “positive messages” and “harmful information” — are likely to concern social media users in the country, especially the 250 million that use microblogging service Sina Weibo. What constitutes news and information to Weibo users could well be seen as harmful by those in Beijing.

For example, the government recently witnessed how social media is stopping it from controlling information. Word of a recent train crash in the country’s Zhejiang province spread rapidly through Sina weibo user messages, when typically information of such events would be released in a more controlled manner by the state.

Who is to say that, were a similar example to take place again, the government couldn’t prosecute Weibo users reporting the accident for spreading harmful information?

It’s worth bearing in mind that most Chinese online services already have ‘content management’ teams which deal with information or messages that might cause issue with the Chinese government. The addition censorship from the government comes on top of this system, demonstrating that the state sees cause for further, more official regulation.

Though for now there are no concrete details, other than the existence of the agreement exists and ‘support’ for it, so we will have to wait to learn more. While Sina, Baidu, Alibaba and others will be keen to satisfy the government on one hand, they will also seek a balance which keeps users happy as is possible to prevent losing business or popularity – but how much control they can maintain?

Social media has grown to the point where it has a phenomenally huge user base, just Sina and Tencent Weibos alone have a combined membership close to 500 million. It remains to be seen what kind of backlash would greet any new restrictions placed on social media in China.

The government has made no secret of its plan to impose limitations on social media. Only last month it admitted to considering the introduction of a real name policy to increase accountability as it seeks to cut the significant influence of social media in China.