Mexican officials have long said the most of the guns used by the cartels are smuggled in from the United States. But Gen. Munguia warned Tuesday that the Mexican gangs that have expanded into Central America are also trying to buy weapons there.

"There is a real threat, that is true," Gen. Munguia told the local television station Channel 33. "All the armies in Central America, the police forces and municipal police, everyone who weapons, should be on alert and take measures to avoid them being stolen."

"The Mexican cartels have set up a sort of rear guard for themselves in Central America, a logistical base," Munguia said. "The cartels that operate in southern Mexico and in Guatemala are trying to supply themselves with weapons in the Central American area."

Officials in the region say Mexican cartels, and particularly the Zetas cartel, have set up operations in Central America because they see it as a valuable area for shipping and producing drugs.

On Monday, Salvadoran military intelligence agents caught a junior officer who deserted the armed forces in December. He allegedly had three assault rifles and uniforms that he was trying to sell to a civilian who officials believe was trying to obtain the weapons for a drug gang, possible Mexico's Zetas cartel.

"Some civilians wanted to buy weapons, and these civilians supply weapons to some criminal groups in Guatemala," Munguia said. "We believe they are connected to drug cartels, and the Zetas in particular."

The previous week, the army arrested two noncommissioned officers and four soldiers who allegedly tried to steal and sell 1,812 grenades.

Munguia acknowledged that the cartels in northern Mexico, where most of that country's drug-related violence is centered, continue to get their weapons from the United States.

The U.S. government says many guns used by Mexican cartels are bought in the United States.