An association comprising major social media service operators Wednesday urged its member firms to ban solicitation of suicide-pact partners through their sites, following a serial murder case near Tokyo in which the suspect is alleged to have contacted Twitter users who expressed suicidal thoughts.

The association, formed in July this year to improve internet safety for children and young people, includes CyberAgent Inc., DeNA Co., Facebook Japan, Gree Inc., LINE Corp. and mixi Inc.

The group is urging member firms to limit access to their services by users who offer to help people commit suicide, and to cooperate with police more closely when they find particularly alarming posts.

In the murders in Zama just outside Tokyo earlier this year, Twitter was the key communication tool that brought together the suspect and some of the nine victims. The suspect used a Twitter account to boast of their knowledge about hanging in order to make contact with people who wanted to commit suicide.