United Nations troops have been accused of killing two civilians in eastern Democratic Republic of the Congo as the body's first offensive force is dragged into an escalating conflict.
On Saturday, scores of angry residents took to the streets, complaining that the UN had not done enough to protect them. A UN car was set ablaze and, when the crowd allegedly tried to storm a UN base, two protesters were killed.
Witnesses claim that UN troops from Uruguay opened fire on the demonstrators, but the Uruguayan president, Jose Mujica, denied this, insisting that they only fired rubber bullets and it was Congolese police who used live ammunition.
The UN has opened an investigation into the incident, which has the potential to embarrass the 3,000-strong "intervention brigade" that was created in March and entered combat last week against the M23 rebel movement.
The US state department said: "We urgently call on (Congolese) and Rwandan governments to exercise restraint to prevent military escalation of the conflict or any action that puts civilians at risk. We reiterate our call for Rwanda to cease any and all support to the M23." Rwanda has repeatedly denied UN allegations that it backs the M23 rebels.