A new South Korean thriller about Internet-obsessed youngsters is seeking to shed light on a growing culture of cyber-bullying in a country with one of the world's highest youth suicide rates.

"Socialphobia", which received its world premier at the 19th Busan International Film Festival on Saturday, follows two nascent cyberbullies who become targets themselves.

The first feature film by director Hong Seok-Jae offers a vivid, detailed portrayal of the South's vibrant yet highly volatile online landscape, where a petty online debate can quickly escalate.

South Korea is one of the world's most wired nations, with broadband Internet omnipresent and more than 70 percent of the population owning smartphones.

Major Internet portals prominently display hourly updates on the latest trending topics -- a practice critics accuse of fanning a herd mentality.

Aggressive cyber bullying, especially targeting celebrities, has been blamed for numerous suicides in recent years including the death of a leading actress in 2008.

It is against this backdrop that the film's main characters -- aspirant police officers named Kim Ji-Woong and Ha Yong-Min -- get embroiled in an Internet witch hunt involving a young woman.

Angered by her tweet about a young soldier killed on duty, netizens unearth the woman's real name, photo and home address.

A group of young men, including Kim and Ha, then organise a trip -- live broadcast on a video-streaming website -- to her home where they find her dead after apparently hanging herself.

The two young men then become the targets of a cyber backlash, as they are blamed for her suicide.

Seeking redemption, the boys convince themselves that the girl was murdered and set out to investigate her past.

The plot and its characters were inspired by real-life events and Internet commentators, Hong said in an interview with AFP.

"South Korea has such an overgrown Internet community where young people continually form an anonymous clique and look for a battle against some perceived 'enemy'," the 31-year-old said.

"For many, bullying seems to have become another form of online game they play," he added.

Plot rooted in reality

In 2008, a young Seoul woman who wrote a series of vicious comments about a judo star on his blog came under intense attack, and was subjected to a bout of "ID stripping".

The process, which also features in Hong's film, involves hacking an individual's personal information, gathering every comment he or she has posted on the Internet, and then displaying it all online for ridicule.

In the 2008 case, a group of young men went to meet the woman in person, with thousands watching on a live vide-stream.

The attacks extended to her family, friends and even her college professors -- until she was forced to offer an apology.

"I was one of the thousands who watched the whole thing unfold live on the Internet, and was left so shocked," Hong said.

"That happened even before Facebook or Twitter became part of our lives. I thought something like this would be more and more common in the future and I should make a film about it," he said.

South Korea has the highest suicide rate among members of the Organisation for Economic Cooperation and Development, with an average of 33.5 people per 100,000 taking their lives in 2010.

The figure equates to nearly 50 suicides a day.

In one of the most high-profile cases, top actress Choi Jin-Sil committed suicide in 2008 after rumours about her personal life spread on the Internet.

A popular TV sports presenter also died after jumping from her apartment in 2011 following weeks of bullying on Twitter that involved hundreds of sexually abusive messages.

Hong said the dystopian online community described in "Socialphobia" may appear far fetched -- for now.

"But I think this is something we all will have to deal with sooner than we think," he said.