Facebook is testing a feature in the US that asks users if they are worried somebody they know is becoming an extremist.
Other users may also receive an alert saying they may have been exposed to extremist content.
The trial messages are part of Facebook’s Redirect Initiative which aims to combat extremism.
The pop-ups redirect users to a support page.
“This test is part of our larger work to assess ways to provide resources and support to people on Facebook who may have engaged with or were exposed to extremist content or may know someone who is at risk,” a Facebook spokeswoman said.
The tech firm is working with non-governmental organisations and academic experts on this project, she added.'
'Becoming an extremist?'
Screenshots of the pop-ups were posted on social media.
One asked: “Are you concerned that someone you know is becoming an extremist?”
“You may have been exposed to harmful extremist content recently,” another said. “Violent groups try to manipulate your anger and disappointment.
“You can take action now to protect yourself and others.”
Both prompts direct users to a page with support related to extremism.