Rebel gunners fought artillery duels with Muammar Gaddafi's forces in eastern Libya on Friday and Western warplanes struck at heavy armour used by the government to crush the revolt.
The African Union (AU) said it was planning to facilitate talks to help end war in the oil producing country. But Nato said its no fly zone operation could last three months, and France cautioned the conflict would not end soon.
In Washington, a US military spokeswoman said the coalition fired 16 Tomahawk cruise missiles and flew 153 air sorties in the past 24 hours targeting Gaddafi's artillery, mechanized forces and command and control infrastructure,
Western governments hope that such raids, launched a week ago with the aim of protecting civilians, will also shift the balance of power on the battlefield in favour of the Arab world's most violently resisted popular revolt.
In Tripoli, residents reported another air raid just before dawn, hearing the roar of a warplane, followed by a distant explosion and bursts of anti-aircraft gunfire.
Rebel forces massing for an attack on the strategically important town of Ajdabiyah fired steady bursts of artillery at army positions after Gaddafi's forces refused a ceasefire offer.
Opposition forces on the road to Ajdabiyah seemed more organised than in recent days, when their disarray stirred doubts about their ability to pose a challenge to Gaddafi.
They had set up road blocks at regular intervals and Reuters counted at least four truck-based rocket launchers -- heavier weaponry than had been seen earlier this week.
At the African Union headquarters in Addis Ababa, AU commission chairman Jean Ping said it was planning to facilitate talks to help end the conflict in a process that should end with democratic elections.
It was the first statement by the AU, which had rejected any form of foreign intervention in the Libya crisis, since the U.N. Security Council imposed a no-fly zone last week and began air strikes on Libyan military targets.
But in Brussels, a Nato official said planning for Nato's no-fly operation assumed a mission lasting 90 days, although this could be extended or shortened as required.
France said the war could drag on for weeks.
"I doubt that it will be days," Admiral Edouard Guillaud, the head of French armed forces, told France Info radio. "I think it will be weeks. I hope it will not take months."
Guillaud said a French plane destroyed an army artillery battery near the eastern frontline town of Ajdabiyah, 150 km (90 miles) south of Benghazi. Ajdabiyah is strategically important for both sides as it commands the coastal highway to the west.
In London, the Ministry of Defence said British Tornado aircraft had also been active there, firing missiles overnight at Libyan military vehicles threatening civilians.
In the eastern rebel bastion of Benghazi, rebel spokesman Mustafa Gheriani said he expected Ajdabiyah to fall on Friday or Saturday following the overnight British and French strikes.
"This (the strikes) will weaken their forces and more importantly their morale," he said, adding the level of Western strikes was "sufficient. We feel safe under their protection".
Simon Brooks, head of the International Committee of the Red Cross operations in eastern Libya, reported big population movements from the Ajdabiya area because of the fighting.
The ICRC was sending 700 tents west of Ajdabiya to help these displaced people, he said In Ajdabija, the hospital "is obviously very close to where the fighting is going on. It is extremely difficult for people to get access to the hospital."
Officials and rebels said aid organisations were able to deliver some supplies to the western city of Misrata but were concerned because there were still government snipers in the city centre.
A resident of Zawiyah, just west of Tripoli, said residents were staying indoors in a climate of fear after heavy fighting, with some residents subject to beatings and kidnappings.
"It's a ghost town. Gaddafi's men are still firmly in control but they are facing resistance from the rebels in some streets," said Mohsen, who fled to the Tunisian border on Wednesday. Gaddafi's forces took back control of Zawiyah, about 50 km (30 miles) west of Tripoli, two weeks ago.
Nato said on Thursday that after four days of tough negotiations that it would enforce the no-fly zone but stopped short of taking full command of U.N.-backed military operations to protect civilians from forces loyal to Gaddafi.
SUDAN SAID TO SUPPORT NO FLY ZONE
Differences over the scope the U.N. resolution gave for military action against Gaddafi's army led to days of heated arguments within Nato about its role in the operation.
The United States, embroiled in Iraq and Afghanistan, is keen to step back and play a supporting role in Libya in order to preserve alliance unity and maintain the support of Muslim countries for the UN-mandated intervention.
Despite the apparently cumbersome structure of the planned new command and Arab jitters on the use of force, the operation continues to receive support from beyond Western ranks.
At the United Nations, envoys said Sudan had quietly granted permission to use its airspace to nations enforcing the no-fly zone. Sudan's UN ambassador, Daffa-Alla Elhag Ali Osman, neither confirmed nor denied that report.
South of the Sahara, local media quoted a cabinet minister as saying Uganda would freeze Libyan assets worth about $375 million in line with a U.N. resolution imposing sanctions on Libya following Gaddafi's violence crackdown.
The UAE said it would send 12 planes to take part in operations to enforce the no-fly zone.
Qatar has already contributed two fighters and two military transport planes to help enforce the no-fly zone.
Western jets pounded targets in southern Libya on Thursday but failed to prevent government tanks re-entering Misrata, whose main hospital was besieged by government snipers.
LIBYA NOT COMPLYING WITH RESOLUTION
In Tripoli, a Libyan energy official said on Thursday Libya was short of fuel and needs to import more, but a ship with fuel now bound for Tripoli may be stopped by Western forces.
Officials and hospital workers said civilians, including women, were among those killed in the latest Western air strikes in the Libyan capital. There was no way to independently verify the report.
A preacher addressing Friday prayers at Tripoli's Ahmad Basha Mosque, and broadcast live by state run Shababiyah TV, urged Libyans "to confront this new crusader war".