Ajdabiya is one of the cities where fierce fighting has been taking place Fighting has been continuing in Libya for key cities after a fifth consecutive night of air strikes.
Overnight several loud explosions were heard in TripoliIn Misrata, a rebel-held city east of the capital, government tanks have been shelling the area near the hospital.
There have also been reports of fierce fighting between rebels and pro-Gaddafi forces in strategic Ajdabiya. Residents fleeing the town described shelling, gunfire and houses on fire.
In Misrata, Libya's third-largest city, witnesses had said on Wednesday that tanks had pulled back from their positions under air assault from international forces.
But later residents said the tanks had rolled back into the city and resumed shelling.
An explosion was also reported at a military base in the Tajura region east of Tripoli.
Residents in Tripoli said plumes of black smoke could be seen coming from an area near a military base, although this has not been independently confirmed.
Earlier, the US chief of staff for the mission in Libya insisted there had been no reports of civilian casualties caused by allied action.
Rear Admiral Gerard Hueber's comments come despite claims to the contrary by Muammar Gaddafi's government.
Operational control
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After one particularly loud explosion during the night, a column of smoke was seen rising from the direction of a military base in the city. There have been various bursts of prolonged firing from the ground, completely useless in terms of hitting the planes or missiles involved, but often an indication that the defenders think they are coming under attack.
There are contradictory accounts about the effectiveness of coalition attacks on Col Gaddafi's forces outside the rebel-held town of Misrata. On Wednesday, pro-Gaddafi tanks seemed close to taking the town, but after a number of coalition air strikes they appear to have been silenced. Still there are suggestions that the tanks and artillery may have opened up again under cover of darkness.
Misrata is the last major town in western Libya that's been holding out against the pro-Gaddafi counter attack so it's important from the coalition's point of view to protect it from falling.
At the scene
There are contradictory accounts about the effectiveness of coalition attacks on Col Gaddafi's forces outside the rebel-held town of Misrata. On Wednesday, pro-Gaddafi tanks seemed close to taking the town, but after a number of coalition air strikes they appear to have been silenced. Still there are suggestions that the tanks and artillery may have opened up again under cover of darkness.
Misrata is the last major town in western Libya that's been holding out against the pro-Gaddafi counter attack so it's important from the coalition's point of view to protect it from falling.
Earlier, British Air Vice Marshal Greg Bagwell said Col Gaddafi's air force no longer existed as a fighting force.
AVM Bagwell said the allies could now operate "with near impunity" over the skies of Libya and were now applying unrelenting pressure on the Libyan armed forces."We are watching over the innocent people of Libya and ensuring that we protect them from attack," he said. "We have the Libyan ground forces under constant observation and we attack them whenever they threaten civilians or attack population centres."
His comments came as Nato members debated who should lead the intervention, with the US keen to hand over operational control to Nato.
Nato members have been holding talks about assuming responsibility for the no-fly zone over Libya, so far without agreement.
Turkey is an integral part of the naval blockade, but has expressed concern about the alliance taking over command of the no-fly zone from the US.
US Secretary of State Hillary Clinton has again urged Col Gaddafi to step down and leave Libya.
UN Secretary General Ban Ki-moon has urged all sides in Libya to cease hostilities. "All those who violate international humanitarian and human rights law will be held fully accountable," his spokesman Martin Nesirky said.
US Defence Secretary Robert Gates is in the Egyptian capital Cairo for talks on both Libya and Egypt's hoped-for transition to democracy following the fall of Hosni Mubarak.
http://www.bbc.co.uk/news/world-africa-12845178