Facebook is trying to crackdown on sales of guns, illegal drugs, tobacco products or prescription pharmaceuticals, through its website. The company said today that it would monitor and delete posts where users discuss controversial or objectionable subjects that could break the law, such as to sell a gun without a background check or transport it across U.S. state lines.

Any time Facebook receives a report on Facebook about a post promoting the private sale of a commonly regulated item, the company will send a message to that person reminding him or her to comply with relevant laws and regulations. Facebook will also also limit access to that post to people over the age of 18.

Facebook will also require Pages that are primarily used by people to promote the private sale of commonly regulated goods or services to include language that clearly reminds people of the importance of understanding and complying with relevant laws and regulations, and limit access to people over the age of 18 or older if required by applicable law.

The social network will also provide special in-app education on Instagram for those who search for sales or promotions of firearms.

"We will not permit people to post offers to sell regulated items that indicate a willingness to evade or help others evade the law," said Monika Bickert, Head of Facebook's Global Policy Management.

The world's largest social network is responding to criticism from advocacy groups, such as Mayors Against Illegal Guns, which have lobbied Facebook for months to regulate users' posts about firearms for sale on their profiles and group pages.

Facebook already prohibits or restricts advertisements about illegal drugs, weapons and other regulated products and services.