When Jang Ja-yeon killed herself at her home earlier this month, she not only deprived South Korea of a wildly popular soap star. In a damning letter naming the men responsible for the distress that may have caused her to take her life aged 26, Jang heaped shame on the country's entertainment industry with allegations of sexual abuse and exploitation.

In the seven-page letter, written a week before her death, the star of Boys Over Flowers, South Korea's most avidly watched soap opera, chronicled the sexual and other favours she was expected to extend to progress in the cutthroat "Korean Wave" of TV and film.

After making her debut in a 2006 TV commercial, Jang cemented her fame as a vindictive schoolgirl in the soap, and was awaiting the release of her first two films when she died. Almost one million fans visited her website in the 48 hours after her death, on 7 March.

Her allegations, leaked to the media, have prompted an outcry and forced the police to investigate her relationships with several powerful men.

The villain of the piece, according to South Korean reports, is her agent, Kim Sung-hoon, who is now in Japan following accusations he molested a male model. Jang reportedly claimed Kim had regularly beaten her and forced her to have sex with a string of VIPs, including directors, media executives and CEOs. She was also forced to serve and consume drinks and to act as an escort at golf matches, she wrote.

When police raided Kim's office, they discovered a shower and bed in a "secret room" on the third floor.

Kim has proclaimed his innocence, contesting that the letter was part of an attempt by Jang's former manager, Yoo Jang-ho, to ruin his business. Jang was reportedly in Yoo's office when she wrote the note, copies of which he passed to her family. Yoo is now in hospital recovering from a suicide attempt.

While the police investigate, the South Korean media has finally condemned the industry for the way it treats its most marketable - and usually female - talent.

Film and TV viewers are now wondering how big a part abuse and the demands of "slave contracts" played in a spate of celebrity suicides originally put down to the pressures of fame.

Jang's suicide, initially attributed to lingering depression over her parents' death in a car crash 10 years ago, is one of several among South Korean entertainers over the past year.

Three weeks after Jang's death, South Korea's huge online community is still buzzing. "Popseoul," who runs a celebrity gossip blog, said the actor's suicide was part of a "tragic trend".

"Exploitation and abuse is the dirty secret of the entertainment industry," she said, adding that many top celebrities, as former employees of seedy hostess clubs, were expected to continue "entertaining" producers and directors in their new careers.

"In many instances, the prospective star will meet the VIP alone, who hints at casting her, introducing her to another VIP or sponsoring her lavish lifestyle.

"It's just hushed up. It's part of the process of being a star."

A tragic end

Jang is one of seven South Korean celebrities to have killed themselves in the last six months. Ahn Jae-hwan, a 36-year-old actor, was reportedly mired in debt. Choi Jin-sil (right), 39, was worried she had pressured Ahn into suicide. Model Kim Ji-hoo, 23, was harassed on the net after coming out. Singer Lee Seo-hyun, 30, was also under attack on the net over sexuality. Actor Kim Suk-gyun, 30, was said to have been depressed. Transgender actor Jang Chae-won, 26, left a suicide note online.