(CNN) -- Facebook and its photo-sharing subsidiary Instagram Wednesday announced new policies aimed at stemming online sales of illegal guns.
The social media platforms have agreed to remove reported posts that evade gun laws, restrict minors under the age of 18 from viewing posts about firearm sales and provide education to better inform law-abiding sellers of guns.
"By taking these unprecedented educational and enforcement efforts, we've been able to strike an important balance in helping people express themselves, while promoting a safe and responsible community," Monika Bickert, Facebook's head of global policy management, said at a news conference.
The new rules come after campaigns by gun safety organizations nationwide have pushed for stricter controls on the sale of firearms.
Moms Demand Action, an organization devoted to gun-control reforms, started on a Facebook page in December 2012, shortly after a gunman killed 20 first-graders and six staff members at Sandy Hook Elementary School in Connecticut. The organization lobbies for more restrictive gun policies that protect the safety of children and families.
Moms Demand Action founder Shannon Watts said more than 230,000 Americans signed the group's petition, tweeted or used other social media to ask Facebook and Instagram to crack down on online sales. The organization last year campaigned for Starbucks to ban guns in stores, resulting in an open letter by CEO Howard Schultz telling customers to leave guns at home.
Mayors Against Illegal Guns, the largest gun violence prevention group, which was founded by former Mayors Michael Bloomberg of New York and Thomas Menino of Boston, discussed the issue with Facebook officials.
"People are logging onto the Internet and signing into what has become, unfortunately, a virtual gun show," John Feinblatt, chairman of Mayors Against Illegal Guns, said in a conference call Wednesday.
In November, New York State Attorney General Eric Schneiderman joined efforts to persuade Facebook and Instagram to issue new gun rules.
"Responsible social media sites know that it is in no one's interest for their sites to become a 21st century black market in dangerous and illegal goods that place our families and communities at risk," Schneiderman said in a statement.
Facebook already prohibits ads for the sale of guns or ammunition, said Bickert, adding that the new rules will strengthen that policy.
Neither Facebook nor Instagram are e-commerce sites, but both facilitate conversation and provide an open marketplace that makes it possible to exchange information promoting weapons sales.
Gun sales listed by site users talked about "no background check required" or said "will cross state lines," Feinblatt said.
Law enforcement officers and advocacy groups will have a direct connection to Facebook to flag posts that may promote this illegal activity, officials said.