San Francisco - Facebook has banned people using the social network for unlicensed gun sales after pressure from anti-gun violence groups alarmed over the ease with which firearms are sold online in the United States.
Although Facebook and its Instagram photo-sharing service do not participate in outright gun sales, the sites have been a forum for negotiations.
The California-based social network on Friday updated its policy for managing regulated goods to prohibit people who aren't gun dealers from using Facebook to offer guns for sale or negotiate private sales of firearms.
"Over the last two years, more and more people have been using Facebook to discover products and to buy and sell things to one another," Facebook head of product policy Monika Bickert said in an email response to AFP.
The policy change, however, will not affect licensed gun dealers who tout their wares on the social network, which is used by 1.59 billion people monthly.
Facebook has similar restrictions on regulated goods such as prescription and illegal drugs. Facebook and Instagram in 2014 restricted posts about buying or selling guns to users 18 years of age or older.
The social network has been under political pressure in the United States to prevent posts that could result in people sidestepping gun-buying laws or background checks.
Gun control groups - some of which have been pressuring Facebook for years to tighten firearms sales on the site - were jubilant about the policy change.
"A big thumbs up to Facebook for taking this important step!," said Dan Gross, president of The Brady Campaign to Prevent Gun Violence, in a statement issued after the announcement.
"The Brady Campaign urged Facebook to bar unlicensed gun sales in 2014 and we are happy to see that Facebook has finally adopted our policy," he said, adding that the move "will help keep guns out of the hands of dangerous people."
An anti-gun group, Moms Demand Action for Gun Sense in America, said it was the fruition of two years of concerted pressure on Facebook by it and other groups.
Those efforts, said "Moms" founder Shannon Watts, led to "new policies to curb children's exposure to guns and to clarify state laws around selling and buying guns online."
"Our continued relationship with Facebook resulted in today's even stronger stance, which will prevent dangerous people from getting guns and save American lives," Watts said.
An affiliated organization fighting for stiffer gun control in the United States, Everytown for Gun Safety, said it had launched an undercover investigation which showed that criminals often flock to the Internet when making illicit firearms purchases.
"We're thankful that Facebook has listened to our call and shut down a key avenue that criminals have used to avoid background checks and buy guns with no questions asked," said the group's president John Feinblatt, who urged other social network sites to follow suit.
Earlier this month, President Barack Obama announced a series of executive orders to tighten regulations on firearm sales - including those conducted online.
Obama's measures would strengthen the existing background check system, and allow health care providers to report names of mentally ill patients into the database.