An apparent Nato airstrike has slammed into a rebel combat convoy, killing at least five fighters and sharply boosting anger among Libyan anti-government forces after the second bungled mission in a week blamed on the military alliance.
The attack - outside the strategic oil port of Brega - brought fresh questions about co-ordination between Nato and the patchwork of rebel militias in a conflict described by a senior US commander as a stalemate that could eventually require the Pentagon to reassert more power, and possibly even send in ground forces.
Tensions between the rebels and Nato were flaring even before the latest accident, with the fighters criticising the alliance for doing too little to help them.
A rebel commander described the attack as a likely Nato accident, but said it would be a "bigger mistake" if it was waged by Muammar Gaddafi's pilots and exposed holes in Nato's efforts to ground Libyan war planes.
In a sign of the hair-trigger tensions along the front, thousands of civilians and fighters raced out of the rebel-held city of Ajdabiya in eastern Libya after reports that Mr Gaddafi's forces gained ground in the chaos after the bombing.
Some militiamen shouted insults against Nato as they retreated.
In Brussels, Nato did not directly acknowledge responsibility for a blundered airstrike on the rebels, but noted that the area where the attack occurred was "unclear and fluid with mechanised weapons travelling in all directions.
"What remains clear is that Nato will continue to uphold the UN mandate and strike forces that can potentially cause harm to the civilian population of Libya," the alliance said in a statement.