Hong Kong, Nov 26 - Police in Hong Kong were Thursday trying to trace the founder of a Chinese-language Facebook group whose members claim to be planning a mass suicide on Dec 21.

The investigation was triggered after a 15-year-old member of the group was stopped by friends as she tried to throw herself off the roof of a Hong Kong school a fortnight ago.

Police found she was one of 190 people who had signed up to the Facebook group called "I have to practise suicide". The group has been removed from the popular social networking site.

Members shared tips on the best ways to kill themselves and goaded each other to join in a mass suicide on Dec 21. A social worker who interviewed the suicidal schoolgirl alerted police.

Some reports in Chinese-language newspapers Wednesday said the group had been disbanded while others quoted members saying that a core "suicide team" remained active.

Headmasters from 35 schools have been contacted about the Facebook group and advised on how to monitor students for any signs that they may be involved, police said.

Youth suicide rates are notoriously high in the wealthy city of seven million with experts saying the pressure to achieve good grades in school and emotionally detached parents are to blame.

Hong Kong's overall suicide rate has fallen markedly in recent years thanks to initiatives such as erecting suicide barriers on tall buildings and putting helpline labels on packets of charcoal. Burning charcoal in a confined space to produce carbon monoxide is a common suicide method in Hong Kong. (dpa)