By JUAN FORERO
 
BOGOTÁ, Colombia, Oct. 8 - A proposal by a coalition of rightist paramilitary groups to disarm 3,000 fighters was presented Friday to President Álvaro Uribe, a gesture that may reinvigorate deteriorating peace talks and lead to the largest one-time demobilization of insurgents in Colombia's 40-year conflict.

The 15,000-member United Self-Defense Forces of Colombia, a coalition of outlaw antirebel forces responsible for drug trafficking and mass killings, described its offer as a "great act of faith." The announcement, made Thursday, came days after the magazine Semana released transcripts of disarmament talks that showed them near collapse.

Diplomats and experts on Colombia's conflict reacted cautiously to the development. They say there is no legal framework for the demobilization of top commanders or a plan to reincorporate 3,000 former fighters into Colombian society by the end of the year, as proposed.

"The government cannot just tell them to demobilize without telling them what they're demobilizing into," said Sergio Jaramillo, director of Ideas for Peace, a policy analysis group in Bogotá. "It is imperative that a law be passed, quickly, so people know what the terms of reference are."

The talks, which officially began July 1, have in recent weeks exposed the extent to which several paramilitary units control northern Colombia, including lucrative cocaine-trafficking routes and businesses where drug profits are laundered.

Through its infiltration of Colombian institutions, including the security forces, regional governments and even Congress, the group has a level of power that even Colombia's most notorious drug trafficker, the late Pablo Escobar, never had.

"They're the most effective cartel in Colombian history," said one high-ranking Western diplomat.

For Mr. Uribe, a disarmament deal with the paramilitary forces is central to maintaining his high popularity and winning support for legislation that would let him run for reelection in 2006.

The paramilitary forces, though, have shown little willingness to give in to demands that they pay in jail time and reparations for war crimes while handing over huge tracts of land obtained through drug money or illegal seizures.

Instead, the groups have extended their presence in more than a third of Colombia's 1,100 municipalities, with nearly 30 mayors and 400 town council members openly expressing sympathy. Though paramilitary commanders claim to have called a unilateral cease-fire, the government's human rights ombudsman has identified 342 violations in 23 months, including assassinations of union leaders and mass killings of Indians.

"There have been so many blows to the talks lately," said Adam Isacson, a senior analyst at the Washington-based Center for International Policy who closely tracks Colombia's war. "They had to do something to show that these talks are viable, but this disarmament is just a pledge and a promise."

The Semana tapes showed paramilitary leaders in a state of near panic over the possibility of being extradited to the United States on drug charges. But in the tapes, Luis Carlos Restrepo, the government's peace negotiator, is heard assuring commanders that the government would try shielding them from extradition, and from facing war crimes trials in the International Criminal Court.

Mr. Restrepo also plays down reports of killings inside a 142-square-mile safe haven in northern Colombia that the government ceded to the paramilitary groups - sharply contrasting with how Colombia's government reacts to reports of killings in rebel-held territories.