Colombia's government and Marxist FARC rebels will announce on Wednesday that they have reached a final peace agreement, three officials connected with the government negotiating team said.
A deal would aim to bring an end to a half century of conflict with the Revolutionary Armed Forces of Colombia (FARC) that has killed more than 220,000 and displaced millions.
"We are facing an imminent deal to close the negotiations," one of the sources said, adding that it was unclear what time the announcement would come. "It will probably be in the evening."
"The main issues have been finalized."
Earlier in the day, FARC guerrilla leader Timoleon Jimenez, known as Timochenko, tweeted: "We are at the doors of important announcements that bring us close to the final deal."
The historic accord would foresee the demobilization of guerrillas, rebel reintegration into civil society and participation in politics.
Reached after almost four years of fraught talks in Cuba, the deal would still need to be signed and voted on in a referendum. Most opinion polls suggest Colombians will back the deal.
Peace with the FARC does not guarantee an end to violence in Colombia. Talks between the smaller, leftists National Liberation Army (ELN) and the government recently stalled, while gangs born out of right-wing paramilitary groups are reported to have taken over some drug trafficking routes.