Instagram is launching a new suicide prevention tool designed to reach out to users at risk of self-harm.

The new feature will allow people to anonymously flag posts about self-harm and suicide. Instagram will then notify the person who posted the flagged that someone thinks they may be going through a difficult time, and offer them help.

They will be encouraged to either talk with a friend, contact a helpline, or get tips on where to seek help.

"These tools are designed to let you know that you are surrounded by a community that cares about you, at a moment when you might most need that reminder," said Marne Levine, Instagram COO.

The flagged posts will be reviewed by a team of people who are working 24/7, and will not rely on algorithms to judge whether someone is vulnerable.

Instagram already offers some help to people who are at risk of self-harm and suicide. It provides helpline contacts and other support information in its safety guidelines.

But these are only useful if the person has already decided to seek the information. The new tool will allow Instagram and its users to proactively reach out to people who might be at risk.

Samaritans, a leading charity helping people at risk of suicide, called the new tool useful. "Research shows that social media feeds can be effective indicators of what happens in real life...so messages that cause concern shouldn't be ignored," said Samaritans spokeswoman Susan Royal.

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"This tool offers an opportunity for friends and Instagram to reach out to people who may be struggling and signpost them towards sources of support that they may not have otherwise considered, such as Samaritans," she added.

The company said it collaborated with the National Suicide Prevention Line, the Samaritans, and with people who have personal experience with self-injury and suicidal thoughts to build the tool.

"We listen to mental health experts when they tell us that outreach from a loved one can make a real difference for those who may be in distress," Levine said. "At the same time, we understand friends and family often want to offer support but don't know how best to reach out," she added.

Instagram's parent company, Facebook (FB), has introduced similar tools that allow users to report content about suicide or self-injury.

Facebook can then reach out to the user posting this content and offer help and information.