The government of Colombia and Farc rebels have announced that they have reached a deal on reparations for victims of the armed conflict.
The agreement deals with one of the most sensitive issues in the three-year peace talks taking place in the Cuban capital, Havana.
It will include the establishment of a special judicial system to deal with the punishment of war crimes.
Details of the breakthrough will be announced in Havana on Tuesday.
Negotiators from both sides said they would hold a signing ceremony for victims and their families in Havana.
In September, both sides said they had agreed to establish special courts to try former fighters, including guerrillas, government soldiers and members of right-wing paramilitary groups.
The courts would offer amnesties or lower sentences for those who admit their crimes, but exclude from amnesty those responsible for war crimes or crimes against humanity.
The Farc rebels said they would release details on Tuesday of how to punish fighters who laid down their arms.
A Farc representative, Marco Leon, said of the peace process: "With this important step, it is nearly certain that this is irreversible."
Government spokeswoman Marcela Duran said: "We are very pleased with this agreement on [victims] which no doubt is transcendental for what we are doing in this process."
Both sides have promised to sign a final peace deal by the end of March. The only items on the agenda which have not yet been settled are disarmament and the mechanism by which the final accord will be ratified.
The Revolutionary Armed Forces of Colombia (Farc) has been fighting the government since 1964.
It has killed more than 220,000 people and is estimated to have displaced six million.