BEIJING - China's major web portals have signed a commitment to "self-manage" comments on their websites, state-run Xinhua news agency reported.
Internet giant Tencent Holdings Ltd, Sina Corp and Sohu.Com Inc were among 29 websites that signed the pledge, after the Cyberspace Administration of China (CAC) held a meeting to discuss the topic.
The websites promised that users would respect "laws and regulations, the socialist system, the national interest, and the legal rights of citizens". They would not publish comments that reveal state secrets, harm the reputation of the country, or "destroy national unity".
Also, CAC and the State Administration for Press, Publication, Radio, Film and Television held a joint news conference to launch a campaign to clean up web videos, Xinhua said.
The campaign, which will run until the end of the year, is meant to target "harmful" material, such as "obscene sexuality", "violent terrorism" and "false rumours" on a variety of online platforms, including mobile app stores, blogs, online storage sites, unlicensed video streaming websites and Weixin, the popular messaging service developed by Tencent.
Leading online video sites in China include those run by Sohu.Com, Tencent and Youku Tudou Inc, as well as Baidu Inc's iQiyi. It was unclear if the campaign would include them.
The new measures are the latest in an escalating campaign to crack down on unwanted material online. Critics say the increasing restrictions further limit free speech in the one-party state.
Last year, Chinese authorities announced severe penalties for the spreading of what they called irresponsible rumours online.
In September, Xinhua said CAC has closed nearly 1.8 million accounts on social networking and instant messaging services since launching an anti-pornography campaign in April.