Victims of cyberstalking suffer more than victims of 'traditional' bullying, research shows.

The inability to escape from the 24 hour online world and the public nature of threats posted on the internet make being bullied electronically more intense, it was claimed.

The research also found that four out of ten women have suffered electronic harassment after dating online and 20 per cent of online stalkers use social networking to stalk their victims.

Addressing the American Psychological Association's Annual Convention, Elizabeth Carll said: "Increasingly, stalkers use modern technology to monitor and torment their victims, and one in four victims report some form of cyberstalking, such as threatening emails or instant messaging."

Victims may feel stress, anxiety, fear and nightmares, as well as enduring eating and sleeping difficulties, she said.

Dr Carll, of the APA Media Psychology Division, "It is my observation that the symptoms related to cyberstalking and e-harassment may be more intense than in-person harassment, as the impact is more devastating due to the 24/7 nature of online communication, inability to escape to a safe place, and global access of the information."

Some 850,000 adults, mainly female, are the targets of cyberstalking in America each year.

But she said that the strengths of the internet currently being exploited by the bullies could be turned against them.

She said: "The same technologies used to harass can also be used to intervene and prevent harassment.

"Imagine a cell phone application that can tell you if someone threatening you is nearby. That could be life-saving."

Police forces and social services should do more to use electronic methods to stop online harassment, she argued.

The talk came after research showed 36 per cent of students at schools in South Korea had been bullied online at least once in the previous year.

Dr YeoJu Chung, of Kyungil University, said: "The results revealed that cyberbullying makes students socially anxious, lonely, frustrated, sad and helpless.

"Lots of adolescents have trouble recovering from negative effects of cyberbullying.

"We can help them use emotion regulation skills to recover, rather than become bullies themselves."