Two members of Colombia's largest rebel group pleaded guilty Thursday to federal drug conspiracy charges, the first from the organization known as FARC to be convicted of narcotics trafficking in the United States, prosecutors said.

Cesar Augusto Perez-Parra, 43, and Farouk Shaikh-Reyes, 41, pleaded guilty to charges that they plotted to smuggle more than 4,400 pounds of cocaine about once a month from Colombia to Miami. They were arrested last year before they could import any of the drugs, said U.S. Attorney R. Alexander Acosta.

Both were associates of the Revolutionary Armed Forces of Colombia, or FARC, which is designated as a terrorist organization by the U.S. and European Union. Dozens of other FARC members have been indicted on drug trafficking charges, but Perez-Parra and Shaikh-Reyes are the first to be convicted in the U.S., Acosta said.

FARC is believed responsible for more than half of the U.S. cocaine supply.

The guilty pleas, coming on the heels of this week's conviction and sentencing in Miami of the two brothers who founded Colombia's Cali cocaine cartel, demonstrate that U.S. law enforcement officials are not easing up efforts to staunch the flow of the drug, Acosta said.

"With the death of the cartels, U.S. law enforcement has not walked away from Colombia," he said.

The suspected supervisor of the two men who pleaded guilty, Ferney Tovar-Parra, is in custody in Colombia and is awaiting extradition to face similar charges in Miami. He is accused of overseeing FARC coca fields and laboratories and of collecting "taxes and fees" for much of the group's cocaine industry.

Perez-Parra and Shaikh-Reyes could face several decades in prison when sentenced in January by U.S. District Judge K. Michael Moore.

FARC, created in 1964 and dedicated to overthrowing Colombia's government, boasts as many as 20,000 armed guerrillas whom U.S. officials and Colombian officials blame for bombings, murders, kidnappings, hijackings and other violent acts in addition to the drug trade. U.S. prosecutors say FARC uses drug proceeds to purchase weapons.

Gilberto and Miguel Rodriguez Orejuela were sentenced this week to 30 years in prison and ordered to forfeit $2.1 billion in assets after pleading guilty to drug charges stemming from operation of the Cali cartel. That cartel once supplied 80 percent of the world's cocaine but is now essentially defunct.