The Colombian government on Sunday accused left-wing rebels of playing politics with the fate of 63 hostages, including a former presidential candidate and three Americans held by the guerrillas in secret jungle camps.

President Alvaro Uribe last month accepted a proposal by France, Spain and Switzerland to break a deadlock with the Revolutionary Armed Forces of Colombia, or FARC, over starting talks on freeing jailed rebels in return for the hostages.

Although the plan appeared close to meeting the rebels' earlier demands for talks to begin, the FARC responded by saying that while it had not seen the proposal there would be no hostage swap with right-winger Uribe, who is running for re-election next year.

Polls show voters would react favorably to a hostage exchange.

"Obsessed with damaging the prestige of President Uribe they now say say there will be no exchange, as a way of swaying voters toward other candidates," said a statement issued on Sunday by the government's High Commission for Peace.

The hostages include Ingrid Betancourt, a Colombian-French national captured by the FARC while campaigning for the presidency in 2002. The rebels also have three civilian U.S. Defense Department contractors seized in 2003 as well as Colombian politicians, police officers and soldiers held up to seven years.

"The FARC wants the government to pay a political cost for the prolonged captivity of the kidnap victims," the statement said.

The rebels helped former President Andres Pastrana get elected in 1998 by insinuating they could reach a peace deal with him. Uribe was a fierce critic of the Pastrana-FARC talks, which broke down in 2002, saying the rebels must be defeated militarily.

Thousands are killed and tens of thousands displaced every year by Colombia's 41-year-old guerrilla war.

Uribe, popular for cutting crime as part of his U.S.-backed military offensive against the rebels, is expected to win a second four-year term in May.

Accepting a proposal by France, Switzerland and Spain, Uribe last month reversed his long-held refusal to withdraw security forces in order to hold talks. He agreed to clear government troops from around a small mountain town in southern Colombia to provide a safe meeting place from the point of view of the FARC, which funds itself with the country's cocaine trade.

Uribe, whose father was killed by the rebels in the 1980s, last week called the group a bunch of "thieves, buffoons and screamers" for rejecting the gesture.