WASHINGTON - Attorney General Eric Holder has asked the Justice Department inspector general to take another look at the efforts of U.S. agents who hunt gun traffickers along the U.S. border with Mexico.

Some on Capitol Hill have suggested the current strategy endangers law enforcement officers.

Holder's decision was followed Thursday by the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives announcing that it will ask a panel of law enforcement professionals to review the bureau's firearms trafficking strategies.

The ranking Republican on the Senate Judiciary Committee, Sen. Chuck Grassley of Iowa, says he has been told by some personnel at ATF that the agency has allowed assault rifles to be sold to suspected straw purchasers for an illegal trafficking ring. Grassley questions whether agents adequately tracked the weapons after that.

Two of those weapons were recovered at a firefight that killed U.S. Customs and Border Protection agent Brian Terry last December in southeastern Arizona.

CBS News reported Thursday that federal agents acknowledged allowing guns into Mexico as part of a Justice Department-approved plan by ATF to disrupt a drug cartel. Thousands of guns found their way south of the U.S. border because of the plan, and some of the guns began turning up at crime scenes in Mexico, according to the CBS report.

"We just knew it wasn't going to end well," John Dodson, a senior agent who was assigned to the ATF's Phoenix office in 2010, told the network. "There's just no way it could."

CBS reported that Dodson and other senior agents, who were not named, complained again and again to their supervisors about how the strategy appeared to be contributing to the rising violence in Mexico. Dodson and other ATF sources took their concerns to Grassley's office, according to CBS.

The Justice Department turned down a request from Grassley for copies of communications between ATF headquarters in Washington and the agency's Phoenix office after Terry's death.