Around 5,000 members and supporters of the Patriotic Union Party were killed by right-wing paramilitary groups in mid-1980s
Colombian President Juan Manuel Santos has accepted the state's role in the killing of thousands of members of a leftist political party three decades ago.
His statement comes two weeks before the signing of a historic peace accord with the Revolutionary Armed Forces of Colombia (FARC), whose members were killed after another peace agreement in the mid-1980s when they formed the Patriotic Union (UP) political party.
Around 5,000 members and supporters of the Patriotic Union Party were killed by right-wing paramilitary groups, often working with state backing.
"That tragedy should never have happened, and we must recognise that the government didn't take sufficient measures to impede and prevent the assassinations, attacks and other violations even though there was evidence the persecution was taking place," Santos said during an event where 200 survivors and family members of UP victims were present.
The government has also promised to guarantee FARC rebels safety after they give in their arms.
The group has plans to launch a political party and run for office.
"I make the solemn commitment before you today to take all the necessary measures and to give all the guarantees to make sure that never again in Colombia will a political organization have to face what the UP suffered," Santos said.
Earlier this week, he FARC also apologized for kidnapping thousands of people to fund its half century of conflict with the government.
(WION with inputs from Reuters)