Facebook has been criticised by a gun safety group for taking millions of dollars in advertising revenue to promote a legal "loophole" that allows Americans to obtain "concealed-carry" weapon permits without any physical training.
The social network's own records show at least $3.7m (€3.3m) has been spent since May advertising the "Virginia loophole".
It enables would-be gun carriers to get a permit in a few minutes by answering 10 questions on their mobile phone, without ever touching a firearm or meeting an instructor.
A company promoting the controversial scheme has been designated a "political advertiser" by Facebook and has become its third-biggest spender, after Donald Trump and Beto O'Rourke, a leading Democrat.
David Chipman, a senior policy adviser at the Giffords Law Centre to Prevent Gun Violence, said: "A company has choices to make, to look if it's in the interests of their company to support people carrying guns that haven't been trained to use them.
"I would just want them [Facebook] to make that decision with eyes wide open. You don't get that training by answering multiple-guess questions on the internet."
In the state of Virginia, it is legal for non-residents to obtain a concealed-carry licence by taking a test online. Due to reciprocity agreements, these licences can be obtained by people in 30 other states.
The rules in their home state may be much more stringent. For example, thousands of Texans have obtained Virginia licences even though securing a Texas licence would have required hours of training.
Facebook said the adverts did not violate its policies. (© Daily Telegraph, London)