Bullying is a big problem in the digital playgrounds of the world's social networks.

But South Korea's top social networking site Cyworld is touting several distinctive features -- including making people prove who they are in the real world before they can join their virtual one.

This might seem at odds with the whole ethos of social networks such as Facebook and MySpace, but it can be a bonus in a country where cyber bullies have posed a problem.

"Although I think new social networks will take up a certain portion of the Korean market, we are better known, more experienced and have strong privacy protection," Lee Tae-Shin, portal manager at Cyworld, told AFP.

Cyworld, unlike many other open social networks, requires users to verify their real names and identities when creating an account.

"By doing so, we can protect the privacy of our users and we take the matter very seriously," Lee said.

In one of the world's most most wired societies, malicious Internet gossip can wield strong sway. Police in 2008 announced a crackdown on rumour-mongers, whom they blamed for the suicide of local actress Choi Jin-Sil.

Such rumours were also partially blamed for the suicide of actress Chung Da-Bin. A government survey in 2006 showed 85 percent of high school students were under stress from cyber bullying.

One analyst said the privacy policy has both advantages and drawbacks.

"Cyworld's well-protected privacy allows a tight relationship between 'friends'. But that prevents networks from expanding," said Han Sang-Ki, a professor at KAIST's Graduate School of Culture and Technology.

But at least one active user is enthusiastic.

"It's much easier to set up privacy settings on Cyworld than on other systems and that is a huge advantage -- because there is some information which I don't want to reveal, like wallposts, to my friends," said Kim Hoo-Yeon, 21.

Cyworld, founded in 2001, now has more than 20 million South Korean users.

It sees itself as the social network pioneer in one of the world's most wired societies -- with about 78 percent of the population connected to the Internet and some 66 percent of the total using social networks,

Cyworld is a bulletin board for complaints, opinions and even press releases for public figures ranging from Olympic figure skating champion Kim Yu-Na to top politicians.

When Kim broke up acrimoniously with her Canadian coach Brian Orser, she used her Cyworld homepage to explain her reasons to millions of fans.

But its dominance is under threat.

Research and consulting group Korean Click says that in June, Cyworld had 22 million visits a month, Twitter 5.1 million and Facebook 2.2 million.

Last month, Korean Click's figures show 18 million for Cyworld, 7.4 million for Twitter and 6.7 million for Facebook.

Despite the trend, Korean Click says it expects domestic social networks to raise their game and compete more dynamically.

Cyworld is trying to do just that. Two months ago it introduced the C-Log, incorporating some features of Facebook and a Twitter-style short message service, to meet the competition.

"It will be an interesting competition. We will do our best," said portal manager Lee.

Cyworld, part of the Nate portal provided by SK Communications, boasts several distinctive features apart from just privacy.

Users can decorate their homepage with background music, wallpaper, postings from diaries, pictures and video footage.

A service called "Ilchon" allows users to become friends and to comment on, or cut and paste, each others' postings.

Cyworld also has an online currency called "Dotori" (chestnuts). Users purchase the online currency and use it to buy background music and other items to decorate their homepage.

Dotori transactions at Cyworld are worth more than 250 million won (220,000 dollars) a day, a major source of profit for SK Communications.

Professor Han says that although Cyworld has more visitors now by far, Twitter and Facebook are catching up fast.

"And at this speed, they might catch up soon," he told AFP.

"About the success of C-Log, we'll have to wait and see.'