The Bureau of Alcohol, Tobacco, Firearms and Explosives is encouraging licensed gun dealers to help private gun sellers run federal background checks.

In an open letter to the country's federally licensed gun dealers, the ATF says they can "enhance public safety and assist law enforcement" by facilitating private sales through their businesses and running federal background checks on prospective gun buyers.

While federal background checks are required to buy a gun from a licensed dealer, the law does not cover sales at gun shows or among private sellers.

The letter was posted on the agency's website hours after President Barack Obama asked Congress to close legal loopholes that allow about 40 percent of gun sales to be done without background checks.