A South Korean vigilante website that published personal details of people it accused of sex crimes suddenly went dark this week after a public backlash sparked by the death of one of its targets, as police hunt for its operators.

Calls have grown for tougher punishment for those guilty of sex crimes after a South Korean man convicted of running one of the world's largest online child pornography operations was released this year from 18 months in jail.

The "Digital Prison" website had listed, among others, 170 people it accused of roles in a network that blackmailed at least 74 women and underage girls into what authorities called “virtual enslavement” by sending them increasingly degrading and violent sexual imagery of themselves.

"Digital Prison is explicitly an illegal website," said Son Jae-woo, chief of a cyber investigation team of police seeking to track down its operators.

The website put up personal details of those it said were criminals, ranging from photographs, names and ages to telephone numbers and employment data, Son told Reuters.

Regulator the Korea Communications Standards Commission said it had been processing an Aug. 14 takedown request from police before the site went offline on Tuesday.

A Seoul university student was found dead early in September following weeks of harassment by strangers after the website featured his photograph and details, police said.

Those behind the website, set up in March, have yet to be identified, despite police arrests of more than 100 suspects in the blackmail ring, including a 24-year-old accused of having founded it.

A message on the website said it existed to serve the public by bringing down social judgment on sex crime suspects despite lenient legal punishment.

Psychiatry professor Chae Jeong-ho said he received hundreds of expletive-laden texts and calls from strangers after he figured on the site.

Police cleared Chae, who works at the Catholic University of Korea in Seoul, but the experience took a toll.

"It would have been easier to heal if I had been beaten by a known suspect, but I felt helpless, as there is no way to tell who is behind this in the cyber world," Chae told Reuters. (Reuters)