The United Nations has said its peacekeepers in the Democratic Republic of Congo were not mandated to stop rebel factions taking control of the eastern town of Bukavu.
The UN praised its soldiers for protecting civilians
The UN spokesman, Fred Eckhard, said fighting had now stopped, massive looting was taking place and UN property had been attacked.
The army lost control of the town after days of fighting against dissident soldiers.
The war in DR Congo ended last year with a transitional government being set up, but many areas have remained volatile.
The UN has become an easy target for the local population's anger at the capture of Bukavu by dissident soldiers.
There were demonstrations outside UN buildings in the capital Kinshasa and the eastern city of Kisangani, and UN vehicles were set on fire.
The UN Security Council has praised the UN peacekeepers' efforts to protect civilians during the fighting in Bukavu.
Regular army soldiers either left or sought refuge with the peacekeepers.
While local people accused UN peacekeepers of allowing the town to fall, UN officials said their mandate was to protect civilians and deter violence.
Fred Eckhard said the peacekeepers were not meant to fight the warring parties.
"The mandate was not to make war. The mandate was based on a peace agreement. Here, the peace agreement has been violently breached. It's for the parties to sort out.
"Once they can sort out their differences and reaffirm their peace agreement, then there's a role for the UN. When war breaks out, the role of peacekeepers ends."
The secretary general has called on all those involved to end their hostilities.
Over the past few days, the UN has boosted the number of peacekeepers in the town from 500 to 1,300.
UN officials said they were carrying out intensive patrols, but if the parties were intent on fighting, there was very little anyone could do to stop them.