The Samaritans has teamed up with Facebook to enable users to report friends contemplating suicide.
Users concerned about a friend will be able to inform the Samaritans through Facebook's Help Centre, where they can report specific content such as status updates or wall posts. Facebook will then put Samaritans in touch to offer support.
The launch follows the death of Simone Back at Christmas, whose contacts failed to raise the alarm after she said she had taken an overdose on the social networking site.
Catherine Johnstone, chief executive of the Samaritans, said: "Through the popularity of Facebook, we are harnessing the power of friendship so people can get help. As a friend you are better placed to know whether someone close to you is struggling to cope or even feeling suicidal.
"We want to remind people that if a friend says that life isn't worth living, they should always be taken seriously. Facebook is a part of daily life for so many of us and we must make sure that people online have support when they need it."
Facebook's director of policy for Europe, Richard Allan, welcomed the expertise and experience the Samaritans could bring to the partnership.
The system has been trialled for three months, during which time it received several genuine reports, says the Samaritans.