The Libyan government has dismissed as "mad" an offer of a conditional ceasefire by rebel forces.
One of the opposition leaders, Mustafa Abdul Jalil, proposed a ceasefire if Muammar Gaddafi's troops withdrew from siege positions around key cities.
But government spokesman Moussa Ibrahim rejected the call, labelling the rebels "tribal, violent, (with) no unified leadership, al Qaida links". He added: "If this is not mad, I don't know what it is. We will not leave our cities and we will not stop protecting our civilians."
His comments come as seven civilians are reported to have been killed in a Nato air strike as efforts to cripple the dictator's military and diplomatic power base continued. The casualties - including three girls from the same family - happened when planes targeted a convoy in the eastern village of Zawia el Argobe.
Shrapnel was sprayed into nearby houses after a truck carrying ammunition was hit, according to the BBC. However, local doctors said the girls' family bore "no anger" towards coalition forces because there would have been a "massacre" if tanks had reached nearby Ajdabiya.
Nato said it was still trying to verify the reports.
The apparent tragedy emphasised the dangers of trying to help the rebels from the air as they struggle to hold off Gaddafi's better-armed and trained forces.
The US has announced that its warplanes will no longer carry out air strikes, although they will be available if assistance is requested by the Nato commander. That will leave the UK, France and Canada responsible for hitting targets on the ground.
Senior British figures voiced concerns about the length of the mission in Libya and its potential for success during a debate in the House of Lords on Friday. Labour's former defence secretary Lord Robertson, secretary-general of Nato from 1999 to 2003, warned that European ground troops might be needed to finish off the Gaddafi regime and provide stability in the wake of the dictator's departure.
But Lord West of Spithead, a former chief of the Royal Navy, warned: "If there were any move towards the use of land forces, I believe we should immediately leave the coalition," he said.