Legislators from all of Mexico's three major parties in congress are calling for a joint U.S.-Mexico working group to examine accusations that U.S. federal agents allowed hundreds of guns to flow into Mexico.

Congressman Humberto Trevino estimated Tuesday that 150 shooting injuries or deaths have been linked to guns that were allowed to proceed into Mexico as part of a U.S. effort to build cases against traffickers.

Two of those weapons were involved in the killing of a U.S. Customs and Border Protection agent in December in southeastern Arizona.

Mexican drug cartels frequently pay straw purchasers to buy weapons at U.S. gun stores and smuggle them south to avoid stringent gun-control laws in Mexico.