The Beijing-based telecom technology company, where the nine people worked, began posting sexually explicit material on their website in 2005 and charged visitors two yuan (about US$0.26) per click, said police without revealing the name of the company.

The website had attracted 8.6 million clicks and the materials had been downloaded 1.3 million times since 2005.

The police arrested nine company staffers, and seized six servers and 10 mainframe computers in a raid on May 9.

According to China's law, if an obscene website receives more than 250,000 clicks, the operators face jail terms ranging from 10 years to life imprisonment.

This case is the single largest case in China involving wireless transmission of illegal pornography.

Beijing has banned the sending of obscene text messages or pictures via mobile phone. Those who are caught doing so face a fine of up to 3,000 yuan (US$385) and two weeks' detention. Those who sell obscene content face jail terms from six months to three years under China's criminal law and the law on public security administration.

China launched a campaign last month to curb the spread of online pornography, and purify the Internet and mobile communication. Police have since closed 1,450 websites and deleted more than 30,000 allegedly obscene messages.