Cyber-bullies who plague internet chat rooms with obscene and insulting comments will be banned under the first national scheme to strip them of their anonymity.

People going online will be forced to provide their real names and social security numbers under a new law that makes internet portals responsible for policing message boards and weblogs.

The law has been introduced in South Korea, and is certain to be closely monitored by other countries where there is concern over online abuse.

The move, which is decried by some as an overly fierce infringement of online liberties, aims to curb the most damaging excesses of so-called “keyboard warriors” – people who concoct sex-scandals, fraud allegations and other libels that chiefly target figures in the public eye.

At least two Korean celebrities are believed to have committed suicide after being subjected to long-running and vicious internet campaigns.

British experts said that cyber-bullying had increased “significantly” in the past five years, and was now a “serious problem” that accounted for a third of all bullying.

Peter Smith, a professor of psychology at Goldsmiths College, London, said, however, that the South Korean measures seemed “heavy-handed” as a first step, and that a better approach would be to educate people about their rights when they are the victims of abusive posts.

“At the moment an ISP in Britain cannot be forced to identify a person who has made a post in a forum unless there is a legal requirement to do so,” said Professor Smith, who is chairman of the research group at the AntiBullying Alliance.

“Victims should be aware, however, that they can request an ISP to instruct a site to take material down if it is threatening or harassing.”

A set of guidelines soon to be issued by the Department for Education and Skills aimed to ensure that children and their parents were familiar with the steps they could take if they found themselves victims of cyber-bullying, he said.

The experience in South Korea, and the reaction of its politicians to the scourge of cyber-bullying is likely to guide governments elsewhere that have begun to look East to Korea and Japan to learn how the next life-changing impact of the internet will take shape.

Because it has the world’s largest population of broadband internet users, Korea has been the first to experience the social impact of the next generation internet, known as Web 2.0. It has led the way in online gaming – and suffered from some of its unintended consequences including attacks in the real world for something that happenbed only in cyberspace.

The legal change is also expected to have a limited impact on cyberspace bullying between schoolchildren – a factor thought to be behind rising suicide levels in South Korea and increased cases of physical violence in schools.

Under the new law intenet portals will be required to give up the real identities of any keyboard warriors when the victims of their cyber-abuse try to track them down to sue them.

Yesterday a spokesman for Daum, a portal site that runs bulletin boards and boasts about 38 million users in South Korea, said it had changed its site so that users must submit their name and social security number before their message is accepted by the server. Another 33 sites – each with more than 300,000 visits per day – are affected by the law.

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