Around 2,000 rightwing paramilitaries in Colombia have laid down their weapons in their last big demobilisation of the peace process.
Leftist rebels have shunned the disarmament process
In all, at least 26,000 members of the United Self-Defence Forces of Colombia (AUC) have disarmed in return for benefits including reduced jail terms.
President Alvaro Uribe says this is the best way to secure peace.
But human rights groups are concerned that paramilitaries who have committed atrocities will go unpunished.
The disarmament signals the end of negotiations between the government and paramilitaries - but few are celebrating, the BBC's Jeremy McDermott reports.
And few Colombians believe an end to the 42-year civil conflict has moved any closer.
The AUC was created to protect ranches from extortion and kidnapping by Marxist guerrillas, but was soon taken over by drug-traffickers.
The political, economic and drugs trafficking structures of the paramilitaries remain intact, our correspondent says.
There is also evidence, he adds, of new paramilitary groups emerging and former AUC factions continuing to operate.
Warning to the left
The northern bloc of the AUC is the last major unit to demobilise as part of the peace process.
Its commander, known as Jorge Cuarenta, is wanted by Washington for drug-trafficking, but is unlikely to be extradited while the peace process continues.
He made a warning at the ceremony to the country's leftist rebels who have not joined the peace process.
"We, the people of Colombia, will not forgive them if they don't take steps toward peace," he said in comments broadcast on television.
Foreign diplomats travelled 690km (420 miles) north from the capital, Bogota, to attend the event in the village of La Mesa.
The peace and justice law, the legislation passed by Mr Uribe to demobilise the AUC, has yet to convict a single paramilitary of any crime, our correspondent notes.
It has been condemned by the United Nations and non-government organisations as offering virtual immunity, even for atrocities that count as crimes against humanity.
In Colombia's congressional election this weekend, candidates sponsored by paramilitary groups are expected to win control of at least 30% of the seats.
Nobody believes the paramilitaries are going to disappear, our correspondent says.