By NANCY SAN MARTIN

A Colombian who allegedly tried to buy more than 6,000 machine guns, rifles, grenades, grenade launchers and pistols for the FARC guerrillas has been arrested in Tampa, U.S. authorities announced Friday.

Carlos Gamarra-Murillo, 53, of Bucaramanga, was taken into custody Thursday by agents of the Immigration and Customs Enforcement after trying to complete the $4 million transaction with U.S. agents posing as arms suppliers. The undercover operation began a year ago.

Gamarra-Murillo, who flew in from Colombia, told the undercover agents he was buying the guns for the Revolutionary Armed Forces of Colombia, the leftist guerrilla force known as FARC.

The criminal complaint filed Friday said Gamarra-Murillo negotiated to pay 60 percent of the cost of the weapons with 15,000 kilograms of cocaine and the rest in U.S. currency.

He gave the agents map coordinates for a clandestine airstrip in Venezuela, where he said FARC representatives would receive the weapons for later shipment to neighboring Colombia.

The weapons to be purchased were 60 M-60 machine guns and grenade launchers, 600 M-16 assault rifles, 720 Galil assault rifles, 500 AK-47 assault rifles, 150 Beretta handguns and 4,000 grenades.

Gamarra-Murillo, who authorities said also had expressed an interest in purchasing Stinger surface-to-air missiles, was charged with violating the Arms Export Control Act. A conviction would incur at least 10 years' prison time and $1 million in fines.