China has shut 50 microblogs for distributing pornography and carrying “vulgar content”, state media said on Monday, as the government steps up monitoring of the internet.

“The microblogs were shut down for violations that include carrying pornographic images and videos, information for prostitution, as well as illegal advertising for sex-related drugs and productions,” Xinhua news agency said.

“Members of the public reported the microblogs, which were then investigated and closed by authorities,” it added, citing an unidentified official at one of the country’s internet regulators, the State Internet Information Office.

The government has called for stricter policing of the nation’s wildly-popular Twitter-like microblogs that more than 200 million Chinese use. Homegrown micro-blogging sites have also served as lively arenas for public discussion over government policies and scandals.

The spread of porn and vulgar material has been effectively contained since a crackdown on Internet- and cellphone-based pornography was launched in 2009, Xinhua said.

“Authorities will continue to take measures to cut down on new channels used for spreading pornography and vulgar material.”

It provided no other details.

China’s microbloggers showed their potency in a string of recent official scandals, particularly an online uproar in the wake of a high-speed bullet train crash in July that killed 40 people. Microbloggers led the charge in challenging rail officials’ evasive accounts of the disaster.

Chinese state media have demanded that Internet companies, regulators and police do more to cleanse websites of “toxic rumors”.

China heavily filters the Internet, and blocks popular foreign sites such as Facebook, YouTube and Twitter.