China says it has shut down 50 websites that were found distributing pornography and "vulgar" content, as Beijing authorities continue their push to police the Internet.

The official Xinhua news agency quotes an unnamed official from the State Internet Information Office as saying the microblogs also were  found carrying information on prostitution and illegal advertising for sex-related drugs and productions.

The report says the shutdowns were triggered by public complaints. It did not say when the complaints were filed or when the shutdowns occurred.

Beijing has called for stricter policing of the nation's wildly-popular microblogs, which are said to be frequented by more than 200 million viewers. In recent months, the websites have carried commentary highly critical of government policies and scandals, including the online uproar that followed a high-speed train crash in July.

Microbloggers heatedly challenged official explanations for the crash that killed 40 people. Chinese authorities later joined in criticizing the probe of the crash and issued public apologies. Several national and regional railway officials also were dismissed.