WASHINGTON – New York City Mayor Michael Bloomberg sharply criticized the White House on Sunday for what he described as its unwillingness to clamp down on illegal gun sales on the US-Mexican border.

The Obama administration recently denied a request by the Bureau of Alcohol, Tobacco, Firearms & Explosives (ATF) for an emergency rule that would force gun dealers on the border to report bulk sales of assault rifles. ATF described it as part of an effort to bust the smuggling of weapons by drug cartels.

Bloomberg, an outspoken advocate for stricter gun laws, issued a statement through his group, "Mayors Against Illegal Guns."

"The White House decided that the illegal trafficking of thousands of semiautomatic assault rifles from the U.S. to Mexico is not an emergency, our coalition of over 550 mayors strongly disagrees," Bloomberg said.

"These guns are fueling violence that has claimed more than 30,000 lives and putting our law enforcement officers at risk. ATF recognizes the emergency but we need the White House to give the agency the support it needs do its job effectively."

The Obama administration has been hesitant to take up the issue of gun control, much to the chagrin of its progressive base. Instead, it has presided over the loosening of various federal and state gun laws.

Numerous gun-control measures were introduced last month in the wake of a shooting spree in Arizona that critically injured a Democratic congresswoman, but none appear likely to be approved.

The pro-gun lobby has outspent the gun-control lobby by a factor of 20-to-1 in the last two decades, according data compiled by the Center for Responsive Politics.

The text of ATF's proposed rule can be viewed here (.pdf).