BEIJING -- Chinese police have closed 598 Web sites in a crackdown on pornography, but online gambling and fraud are growing, state media said Friday.

The latest crackdown, launched in March, led to 25 arrests, the China Daily Newspaper said, citing figures from the Ministry of Public Security. That figure was low compared with more than 500 people arrested in a nationwide crackdown last year.

China has the world's second-largest population of Internet users after the United States, with more than 100 million people online.

The communist government encourages Internet use for education and business but has launched repeated campaigns to stamp out material deemed obscene or subversive.

In the heaviest reported sentence for online obscenity, a 20-year-old Web site operator in eastern China was jailed in 2004 for 15 years for selling downloads of sexually oriented movies.