Colombia's biggest rebel army was betrayed by its own men in last week's military rescue of Ingrid Betancourt and 14 other hostages, the guerrillas said in a statement on Friday.
The group said it remained willing to negotiate a swap with the government of remaining hostages for guerrilla detainees.
The rescue of the kidnap victims -- who included three American defence contractors and had been held for years in secret jungle camps -- was a coup for President Alvaro Uribe that highlighted the success of his U.S.-backed crackdown on the rebels.
The hostages were being guarded by rebel officers Antonio Aguilar, known as Cesar, and Alexander Farfan, known as Enrique Gafas. The pair escorted their captives into a helicopter that supposedly was to take the hostages to see the rebels' leader, but was in fact being flown by Colombian intelligence agents.
The government has said that the pair were tricked into thinking they were going along with a group sympathetic to the rebels. But the FARC accused the two of betrayal.
"The escape of the 15 prisoners on July 2 was a direct consequence of the despicable conduct of Cesar and Enrique, who betrayed their revolutionary ideals and the trust we had put in them," said the statement by the Revolutionary Armed Forces of Colombia, or FARC.
The statement, signed by the FARC's secretariat, was issued on the Bolivarian Press Agency website that often carries rebel statements.
Both the rebels captured last week are under arrest and expected to be extradited to the United States to face kidnapping charges, Reuters reported.