One firm in southwestern Seoul offers a service where brawny tattooed thugs pay visits to the homes of bullies and offices of their parents to threaten them. They also visit victims at schools posing as their uncles so that the bullies can see who they are messing with.

The private investigators gather photographic evidence of bullying and often operate on the very edge of legality by threatening the bullies or harassing their parents.

A growing number of gumshoes offer to intimidate or harass school bullies and are doing brisk business as parents of young victims grow frustrated by the inactivity of schools.

Mostly, however, the gumshoes collect evidence for use in lawsuits. Another firm based in southern Seoul specializes in taking photographs of bullying assaults with long-lens zoom cameras. Each piece of photographic evidence costs W400,000. Staff then take the photos to the schools where the bullying took place and warn teachers that they will file a formal complaint to a district board of education unless action is taken.

Another business in Anseong south of Seoul specializes in harassing the parents of bullies. Staff accost the parents of bullies at their workplace and show them photos of victims' bruises and other wounds. They also threaten to tell the coworkers of the parents about their children's bullying.

If the parents fail to act, they stage noisy protests in front of their offices, "It's better to use our services, since things can get messy if the victim's parents get involved themselves," a staffer said.

Parents of bullying victims claim they have no choice but to resort to these thugs because schools are hopeless at dealing with bullying. Schools are required to convene special inquiries immediately when an instance of bullying is reported, but if they act at all such meetings take weeks to arrange as school officials try to juggle the schedules of teachers, parents, lawyers and other outside experts.

But Kim Yun-tae at Korea University said, "Taking the law into one's own hands to deal with school bullying is simply another form of violence. We need to go through proper steps to deal with such abuses and seek to improve existing measures."