Montenegro on Wednesday extradited to the United States three international arms traffickers who face charges in New York of conspiring to supply Colombia's Marxist FARC rebels with weapons intended to kill Americans.

"Cristian Vintila, 44, Virgil Flaviu Georgescu, 42, and Massimo Romagnoli, 43, were extradited today from Montenegro to the United States of America," Montenegrin police said in a statement.

All three were arrested in mid-December. They face charges of conspiracy to kill US citizens and conspiracy to provide material support to a terrorist organisation.

US prosecutors say they conspired to sell pistols, machine guns and anti-aircraft cannons between May and October this year, knowing they could be used by the FARC against US personnel.

They were arrested following an operation in which they allegedly agreed to supply the weapons on the understanding that they would be used to kill Americans and shoot down US aircraft.

FARC has about 8,000 fighters and is the largest of the guerrilla groups waging Latin America's longest-running armed conflict.

It is currently locked in dialogue with Colombian government negotiators trying to end a five-decade conflict.