BEIJING - China's Internet authorities had closed a total of 277 websites alleged to contain pornography by Thursday, the 11th day of a month-long crackdown on "lewd" online content.

The campaign has extended to cellphone games, online novels, videos and radio programs.

The Ministry of Industry and Information Technology has urged all telecommunications companies to strengthen management of basic operations and cooperate with the government on the crackdown.

A principal of the Special Operation Office for the Crackdown on Online Porn and Lewd Content said, the crackdown was not "flash in the pan", and it would be followed up with more activities.

The campaign was launched on January 5 by the State Council's Information Office, Ministry of Public Security and Ministry of Culture and four other government agencies.

Public distribution of pornography is illegal in China. Previously, the country had blacklisted 50 websites, including search engines Google, Baidu and MSN China, which were accused of providing obscene content and of being slow to delete erotic materials.

According to the China Internet Network Information Center, the country's Internet users hit 298 million by the end of 2008, overtaking the United States as the nation with the world's largest online population.