A senior official highlighted, and condemned, the abuse of social network websites, admitting that managing them posed a challenge for the government.

Networks such as Facebook and Twitter pose new problems for social management, Wang Chen, minister of the State Internet Information Office, said in a keynote speech at the 4th UK-China Internet Roundtable.

"Many people are considering how to prevent the abuse of these networks following violent crimes that took place in some parts of the world this year," he said.

Parts of Britain were rocked by riots in August, many of them organized by utilizing social network sites.

China has more than 500 million netizens, of which 300 million are users of Weibo, the Chinese version of Twitter, he said.

"Everyone involved should observe the law and safeguard the norms of social morality. The Internet should not be used to jeopardize the national or public interest, or the legitimate rights and interests of other citizens," Wang, also minister of the State Council Information Office, said.

As more people, especially the young, get involved in online and virtual worlds, the greater the chance that this could have a negative impact on real life, said Xie Yungeng, a professor at Shanghai Jiao Tong University.

Teenagers can easily be addicted to the Internet. According to a survey conducted by Tianjin-based Nankai University, 68 percent of young people spent more than six hours a day surfing the Internet during their summer holidays.

Zhuan Zhuan, 22, from Qingdao, Shandong province, with about 4,000 fans on Sina Weibo, told China Daily that she always checks her Weibo account whenever she accesses the Internet.

"It's convenient to chat with friends from China or other countries," she said. "But it's very annoying to frequently receive spam massages and rumors."

On Wednesday, a "prostitute" who had more than 250,000 followers, including several prominent Chinese Internet celebrities, on "her" micro blog account, turned out to be a 31-year-old man.

Using the pseudonym "Ruoxiaoan1", the man, surnamed Lin, posted 401 entries on his Sina Weibo account, starting from January, fabricating stories about working as a 22-year-old sex worker who "accidentally" lost her virginity, in Hangzhou, capital of Zhejiang province.

Some of his entries were re-posted as many as 10,000 times.

However, Lin is actually employed as an editor. He craved fame and made up stories on his Weibo account. He was fined 500 yuan ($78) for disturbing public order and his micro blog account was permanently deleted.

Xie Yungeng said that young people are easily influenced by information on social networks, as it is very difficult to distinguish fact from fiction.

There are 212 million Chinese teenager Internet users, accounting for 46 percent of netizens, according to Xie.

"Fraud, porn and violence are easily found on social network websites. All of this can be seen by teenagers, which places them in potential danger," he said.

The professor suggested establishing a law protecting online rights and interests of teenagers.