A Venezuelan-led mission to rescue three hostages held by leftist rebels in Colombia's jungles was on the verge of collapse Monday, with the guerrillas telling Venezuelan leader Hugo Chavez that Colombia's military was preventing the handoff.

Colombian President Alvaro Uribe dismissed the claim as a lie by the Revolutionary Armed Forces

of Colombia, or FARC, saying his government would permit a cease-fire corridor to let the rebels turn over the hostages.

«The FARC terrorist group doesn't have any excuse. They've fooled Colombia and now they want to fool the international community,» Uribe said from the central Colombian city where Venezuela helicopters have been waiting since Friday for word from the guerrillas on where the hostages could be picked up.

Uribe raised the possibility that one of the hostages, a boy thought to be 3 years old and fathered by a guerrilla, could have turned up in Bogota.

The Colombian leader said only DNA tests were required to prove or disprove «this hypothesis» _ which he said could be done as soon as the boy's grandmother returns from Caracas, where she has been waiting for the release of her daughter, Clara Rojas, and grandson Emmanuel.

Chavez said he received a message from the FARC on Monday saying Colombian military operations are preventing them from freeing three hostages they had agreed to turn over to the Venezuelan president _ including the boy, Rojas and former congresswoman Consuelo Gonzalez.

Speaking on Venezuelan state television, Chavez said the rebels wrote in a letter that «the military operational attempts in the zone impede us for now from turning over» the three hostages.

Venezuela and the FARC could consider «another option, a clandestine option» to evade Colombian patrols and turn over the hostages, Chavez said, adding that such a mission could be «extremely risky.

Alternately, Chavez suggested, «a cease-fire could open some doors.

The FARC, in the letter read by Chavez and dated Sunday, said that «insisting on (a handover) in these conditions would be putting at risk» the lives of hostages and guerrillas sent to turn them over.

«The FARC lies. The Colombian government keeps its word,» Uribe responded.

Uribe last month abruptly ended Chavez' efforts to broker a wider swap of 44 high-profile hostages _ including three American defense contractors and former Colombian presidential candidate Ingrid Betancourt _ for hundreds of jailed rebels.

But hostages' relatives have urged the leftist leader on, saying he is the only intermediary capable of breaking a government-rebel deadlock.

The two sides have not held face-to-face talks since Uribe took power in 2002.

The U.S.-allied Uribe has instead used some US$600 million (¤410 million) in annual military and intelligence aid from Washington to push the half-century-old insurgency deeper into the jungle.