Renewed riots have broken out in Liberia's capital Monrovia, as armed gangs of Christian and Muslim youths carried out apparent revenge attacks.
The violence is a reminder of how volatile Liberia remains
The unrest followed clashes on Friday in which at least five people died.
UN peacekeeping troops have detained 80 men for possessing weapons, after sealing off part of a city suburb where the gangs fought running battles.
Sunday was the last day of a UN disarmament programme, in which 95,000 fighters have laid down their weapons.
The figure is nearly double initial estimates. At least 15% of the fighters were child soldiers.
Most observers say the programme has been fairly successful despite Friday's rioting.
However, the uncertain situation has also forced the UN to postpone repatriation of refugees from neighbouring Guinea.
A spokeswoman said the UN refugee agency had hoped to get the repatriation process under way on Saturday, but it had a policy of not returning people to unsafe environments.
She said the repatriation exercise would be started as soon as it became safe to do so.
UN peacekeepers had to fire warning shots and use armoured vehicles in efforts to quell the latest rioting.
Witnesses told Reuters news agency they had seen Christian and Muslim youths fighting with sticks and knives in the city's Paynesville suburb.
The disarmament programme appears to have been a success
Residents fled the scene, holding their hands in the air to show they were unarmed.
It is not clear what sparked the violence, which began on Thursday evening in Paynesville and spread to other districts across the capital including the port area.
Several churches and a mosque were burned down.
Liberia's interim leader Gyude Bryant said hooligans were to blame, but there are reports that former fighters were involved.
The BBC's David Chazan says many are angry at a lack of work and training, but the UN is trying to help solve the problem by putting thousands of child fighters into school.
But the violence was a reminder of how volatile Liberia remains, our correspondent says, and raises questions about the thoroughness of disarmament in a country still awash with guns.
The unrest was one of the most serious outbreaks of violence in Liberia since former President Charles Taylor went into exile in August last year as part of a peace deal to end 14 years of civil war.
Mr Bryant heads a transitional power-sharing government set up to organise elections.
There are some 15,000 UN peacekeepers in Liberia. They are due to finish disarming the estimated 40,000 former militiamen by the end of October.