More than 20,000 paramilitaries have now laid down their arms in Colombia following the latest disarmament drive under the peace process, officials say.
The fighters handed over their weapons in the presence of officials
Over 2,500 fighters of the Central Bolivar Bloc surrendered their weapons at a ceremony in the town of Santa Rosa, north of Bogota.
The government believes this faction controlled a coca production area.
Under the peace process, those who have committed crimes and agree to disarm face reduced prison terms.
Most of the rank-and-file paramilitaries are expected to be pardoned and can be eligible for job-training programmes and a monthly government stipend for two years.
Human rights groups are concerned that paramilitaries who have committed atrocities will go unpunished.
The Central Bolivar Bloc belongs to Colombia's biggest paramilitary group, the United Self-Defence Forces of Colombia (AUC).
Its commander, Carlos Jimenez (known as Macaco), is wanted in the United States for drug-trafficking, but he will avoid extradition.
The fighters handed over their weapons in the presence of Colombian officials and international observers.
As part of the ceremony, they turned over 900 rifles, 90 pistols, 40 revolvers and eight trucks, according to AP news agency.
In a separate development, a Colombian prosecutor issued arrest warrants against two demobilised paramilitary leaders, Carlos Castano and Salvatore Mancuso, in connection with a massacre in the year 2000.
Correspondents say they are unlikely to be arrested provided they observe the terms of the peace process.
The paramilitaries were formed in the 1980s by drug traffickers and cattle ranchers to counter Marxist rebel groups that have been battling the government for more than four decades.