BEIJING-- China's police chief has called for a reinforced nationwide Internet security system, in the nation's latest effort to oversee the activities of the world's largest online population.

"The Internet is developing quickly, there are many loopholes in social management, and maintaining social stability faces unprecedented new challenges," public security minister Meng Jianzhu said in rare public remarks.

"One must... actively establish... a comprehensive prevention and control social security system that covers the Internet and the real world," he said in a speech published on the ministry website Monday.

Internet use has expanded at a dizzying pace in China, which now has the world's largest online population of at least 338 million users.

In a bid to maintain control, authorities regularly censor Internet content they deem unhealthy including pornography and violence, but also information critical of the government -- a system dubbed the "Great Firewall of China."

But many online users get around the system by using proxy servers that allow them to access blocked sites.

The Internet has also become a platform for ordinary people who want to vent their frustrations at perceived injustices.

In one well-known example, a 21-year-old waitress in central China walked free from a trial in June despite stabbing to death an official who demanded sex after the case sparked nationwide Internet outrage about government sleaze.

Such a crime would normally have incurred a serious penalty, such as life in jail or even the death sentence, but apparent official concern over the elevated online outcry is thought to have prompted her release.

The state China Daily newspaper said the government was increasingly concerned about "fake information and new crimes based on the web."

Residents in restive far-western Xinjiang are still experiencing Internet and phone service outages nearly four months after deadly ethnic riots erupted in the regional capital Urumqi.

The government says separatists used the Internet, telephones and text messages to spread rumours and foment hatred as the violence erupted on July 5, leaving 197 people dead, according to an official toll.