The Colombian government and leftist FARC guerrilla fighters have agreed to form a truth commission, as the two sides met in the Cuban capital aimed at ending Latin America's longest war.
Negotiators reached an agreement despite a recent escalation of violence that has threatened the country's peace talks, taking place in Havana.
"The national government and the FARC, we have reached an agreement to put in place, once a final deal has been signed, a truth commission, for coexistence, and in order to not repeat, which will be an independent and impartial mechanism of an extrajudicial nature," said Cuban mediator Rodolfo Benitez, reading the agreement to the media.
"Both the national government and the FARC promised to contribute decisively to the clarification of the truth about everything that happened in the conflict, including serious violations of human rights and breaches of International Humanitarian Law," he added.
Al Jazeera’s Alessandro Rampietti reporting from the Colombian capital, Bogota, said that "this is a positive announcement coming after a very tense round of talks".
"The truth commission will work on clarifying and investigating the worst cases of war crimes and crimes against humanity. It will be independent and extrajudicial in nature," he said.
"It does come with couple of disclaimers. First of all the commission will be formed only after the final peace agreement is signed and also it will not replace other judicial mechanisms to punish those responsible for these crimes.
"It is much needed step forward."
The United States has backed Colombia with billions of dollars of military aid in the fight against leftist rebels and drug trade.
In addition to government troops and the Revolutionary Armed Forces of Colombia (FARC), the war has involved right-wing paramilitary groups, armed criminal gangs and the leftist rebels of the National Liberation Army (ELN).
The 11 commissioners, yet to be selected, are expected to complete the body's task within three years.
Fighting has continued in Colombia during the two-and-a-half years of talks in Havana, adding to a death toll estimated at 220,000. Millions more Colombians have been displaced during the 50-year-old conflict.
In March, Colombian President Juan Manuel Santos had agreed to halt aerial bombing in recognition of a unilateral ceasefire called by the FARC. But he ordered new air assaults in response to a rebel ground attack that killed 10 soldiers in April.
Since then three bombing raids in recent weeks have killed some 40 rebel fighters, and the FARC has renewed offensive operations.
Government and rebel negotiators have reached partial accords on three of five agenda points: land reform, the political future of the FARC and an end to the illegal drugs trade. Still under discussion are victim reparations and the FARC's demobilisation.
Should the two sides reach a comprehensive agreement, it would be submitted to the voters for ratification.