Taking a cue from President Barack Obama's stand on curbing gun violence in the US, social networking giant Facebook has banned private gun sales on its site and mobile photo and video-sharing app Instagram.The Mark Zuckerberg-founded platform on Friday said it was planning to stop person-to-person firearms sales on its networks, cnet.com reported."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," Monika Bickert, Facebook's head of product policy, said in a statement."We are continuing to develop, test and launch new products to make this experience even better for people and are updating our regulated-goods policies to reflect this evolution," Bickert added.The ban, actually an update to a policy that already prohibits the sale of marijuana, pharmaceuticals, and illegal drugs, does not apply to for-sale posts by licensed gun dealers, the report said.Earlier this month Obama had announced renewed efforts to curb gun violence, including expanded background checks.He also sought research into smart guns that, like in one of the James Bond movies, use radio signals or fingerprint scanners to ensure a weapon can be fired only by its owner.