Fighting raged between forces loyal to Libyan leader Muammar Gaddafi and insurgents in several towns on Tuesday despite a UN-mandated no-fly zone aimed at stopping the violence.
Meanwhile doubts persisted over the best way to continue the campaign aimed at preventing Gaddafi's forces from harming civilians in their battle against the rebels, and where it was leading.
Residents of Yafran, 130 kilometres (80 miles) southwest of Tripoli, said at least nine people had been killed when clashes erupted between the two sides.
Rebels also said they were under intense attack in their enclave of Misrata, east of the capital, which has been besieged by Gaddafi's forces for weeks, with four children killed on Tuesday.
The US Africa Command said a US F-15 jet crashed in rebel-held eastern Libya late Monday following a malfunction. Its two crew members ejected and were safe.
Command spokeswoman Nicole Dalrymple said that the crew had sustained minor injuries and that one had been recovered while an operation to pick up the second was ongoing.
She said the aircraft was taking part in a raid to neutralise Libyan anti-aircraft defences but the crash, the first loss of a warplane since the campaign began Saturday, was not a result of hostile action.
After a third night of strikes on Gaddafi's strongholds and defence structure, US Defense Secretary Robert Gates said "significant military fighting that has been going on should recede in the next few days."
Destroying radar and missiles under Gaddafi's control would pave the way for a no-fly zone that could be patrolled by combat aircraft, with the United States assuming a supporting role, Gates said in Moscow.
A resident of Yafran said that "Gaddafi forces launched a deadly offensive in the area on Monday and Tuesday. The fighting killed at least nine people and wounded many."
The resident added, "We had been waiting for the coalition to stop the advance of Gaddafi's battalions into the area.
"In the absence of such an intervention, the regime wanted to take the city quickly by bombarding it and carrying out massacres."
A rebel spokesman reached by telephone in Misrata said the insurgents remained in control despite an onslaught by Gaddafi loyalists who had opened fire with tanks and set snipers on roofs to gun down people in the streets.
The spokesman said five people, four of them children, had been killed Tuesday, a day after a medic in the city confirmed a death toll of 40 and said at least 300 people had been wounded.
Libyan government spokesman Mussa Ibrahim said on Monday that Misrata, Libya's third city 214 kilometres (132 miles) east of Tripoli, was "liberated three days ago" and that Gaddafi's forces were hunting "terrorist elements."
A standoff persisted in eastern Libya, where Gaddafi forces in and around Ajdabiya, south of the insurgents' capital of Benghazi, easily repulsed attempts by the disorganised and ill-armed rebels to advance against them.
Africa Command chief General Carter Ham said Monday that US forces had no mission to support a rebel ground offensive, but at the same time Gaddafi's troops show "little will or capability to resume offensive operations."
Coalition forces, led by the United States, France and Britain and including some other European states and Arab country Qatar, are acting under UN Security Council resolution 1973 authorising "all necessary means" to protect civilians.
There is coordination but no unified command, and moves to hand over control of the operation to the North Atlantic Treaty Organisation are dividing the alliance.
NATO ambassadors resumed talks on Tuesday after "very difficult" discussions on Monday which failed to overcome their divisions.
But a diplomat said they had agreed to use the organisation's naval power to enforce an arms embargo on Libya ordered under UN resolution 1973.
Turkish Prime Minister Recep Tayyip Erdogan ruled Ankara out of sending any combat mission to Libya but said it could take part in operations with humanitarian purposes.
France also has doubts about the impact on Arab countries of NATO taking control -- though the Arab League has backed the no-fly zone -- while Germany refused to vote for resolution 1973.
Norway said Monday its six fighter jets would stay grounded as long as it was unclear who was running the operation, while Britain, the United States and Italy, whose air bases are the main platform for missions to Libya, are pushing the strongest for a NATO role.
Belgian and Spanish warplanes began patrolling Libyan skies on Monday, British Typhoon fighters and Canadian jets launched their first missions from Italian bases and a Greek source said France's aircraft carrier Charles de Gaulle should join in from waters off Crete, probably by Wednesday.
Italian pilots said they had helped suppress air defences, despite Prime Minister Silvio Berlusconi, whose country has close ties with former colony Libya, saying Italian planes "are not firing and will not fire."
Outside criticism persisted, with Russian Defence Minister Anatoly Serdyukov calling for an immediate ceasefire and negotiations between the warring sides in talks with Gates.
Algerian Foreign Minister Mourad Medelci said the Western-led air strikes were disproportionate, amid US and British efforts to bring more Arab states on board.
A spokesman for British Prime Minister David Cameron said London was talking to Arab nations in a bid to "develop" the coalition.
And the White House said US President Barack Obama and Turkey's Erdogan agreed to seek a "broad-based international effort, including Arab states."
Oil prices remained volatile but dipped on profit-taking Tuesday.
New York's main contract, light sweet crude for delivery in April, fell 16 cents to $102.17 a barrel, while Brent North Sea crude for May shed 20 cents to $114.76 in midday London trade.
Meanwhile it emerged that three western journalists who went missing in eastern Libya last week, including two from Agence France-Presse, were arrested by Gaddafi's forces on Saturday.
AFP reporter Dave Clark and photographer Roberto Schmidt, and Getty agency photographer Joe Raedle, had not been heard from since Friday evening.
Their driver Mohammed Hamed said that they ran into a Libyan convoy near Ajdabiya. They turned around, but were caught after a chase by soldiers who shot out their tyres.
Four soldiers ordered the journalists out of their vehicle at gunpoint before putting them into a military vehicle and driving them away.
"We don't know where they were taken," their interpreter Sudki Abdulkarim Jibril told the rebel Radio Tobruk. "They were allowed to keep their telephones but not their cameras."
The UN refugee agency said on Tuesday that thousands of Libyans had fled their homes in the east of the country, taking refuge in homes, schools and university halls.
Adrian Edwards, a spokesman for the office of the UN High Commissioner for Refugees (UNHCR), said people arriving at Libya's border with Egypt feared reprisal attacks by pro-government supporters.