The agreement was signed by the rebels and the government's chief negotiator less than four hours before the scheduled expiration of a huge safe haven President Andres Pastrana ceded to the Revolutionary Armed Forces of Colombia, or FARC, three years ago.
Pastrana, in a nationwide television address, called the accord "an important step" and said he was prolonging the safe haven until April 10.
Cancellation of the zone, a swath of southern jungles and pasturelands twice the size of New Jersey, would likely have resulted in a bloodier war in this South American country.
Foreign diplomats helped facilitate the talks, held under an open-air thatched-roof hut deep in their rebel sanctuary in southern Colombia. After the agreement was reached, government negotiator Camilo Gomez and the envoys toasted the accord with a drink of rum. Cuban Ambassador Luis Hernandez Ojeda handed out cigars to government officials, gun-toting rebels and the diplomats.
"This is good news for Colombia," declared U.N. special envoy James LeMoyne.
The accord signed by Gomez and rebel negotiators calls for immediate opening of cease-fire talks - with the goal of having cease-fire terms ready for signing by April 7 - and the participation of an international verification commission, which would "overcome complications" in the peace process.
"The whole world will be a witness as to whether the FARC and the government are keeping their word," Pastrana said.
The agreement also said talks aimed at ending violence by a brutal right-wing paramilitary group would be part and parcel of the cease-fire negotiations, as would discussions aimed at ending kidnappings by the rebels.
Although the accord called for more talk and not an actual cease-fire, it raised hopes that Colombia's peace process, which began three years ago but has produced few results, was finally on track.
However, there have been disappointments before. A 1984 cease-fire agreement between the FARC and the administration of then-President Belisario Betancur broke down three years later when the rebels ambushed an army patrol. The government then suspended peace talks.
Pastrana revived the peace process after taking office in 1998, taking the novel step of giving the government's enemies a huge safe haven as a site for the talks and as an incentive to the highly suspicious rebels.
However Pastrana, now in his last year of office, has become impatient with the lack of results. Last week, he sent troops to the borders of the huge rebel zone and threatened to retake it unless the rebels returned to the negotiating table, which they had abandoned in October.
He then said that if negotiators failed to agree by midnight Sunday on a timeline for cease-fire talks, he would revoke the guerrilla safe aven.
If the sanctuary had been canceled, the rebels would then have had 48 hours to evacuate the five main towns in the zone.
While talking peace, the FARC has waged an offensive during the past few days, killing 12 government soldiers on Saturday. The president of Congress, Carlos Garcia, said Saturday night that the rebel attacks appeared aimed at pressuring the government and weakening its negotiating position.
Critics of the peace process say the rebels are participating only to buy time and strengthen their forces, currently estimated at 16,000 combatants.
Gen. Fernando Tapias, the commander of Colombia's armed forces, said the military was trying to prevent rebel attacks that have downed power lines in 15 places and heavily damaged a bridge outside the safe haven.
Colombia's civil war kills roughly 3,500 people every year, pitting U.S.-backed government forces and the outlawed right-wing paramilitary group against the FARC and a smaller rebel army.
By Cesar Garcia © MMII The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed