TRIPOLI – Fighting raged between forces loyal to Libyan leader Moamer Kadhafi and insurgents in several towns on Tuesday despite a UN-mandated no-fly zone aimed at stopping the violence.

Meanwhile, as a senior US officer said Kadhafi forces were still attacking civilians, doubts persisted over the best way to continue the campaign to stop Kadhafi, and where it was leading.

French Foreign Minister Alain Juppe said future actions of the coalition, which began air strikes on Saturday on Kadhafi military installations, depend in part of the embattled Libyan leader.

"The military operations could stop at any moment. All it would take is for the Tripoli regime to adhere precisely and completely with UN Security Council resolutions, and to accept a genuine ceasefire," he said.

He called on Kadhafi to withdraw troops engaged in military advances and send them "back to their barracks."

Libyan anti-aircraft fire opened up over the capital after nightfall on Tuesday, amid the sound of far-off explosions, AFP journalists reported.

Residents of Yafran, 130 kilometres (80 miles) southwest of Tripoli, said at least nine people had been killed in clashes between the two sides.

Rebels also said they were under intense attack in their enclave of Misrata, east of Tripoli, which has been besieged by Kadhafi's forces for weeks, with four children killed Tuesday.

But rebels said they had managed to repulse loyalists and retake the outskirts of the western town of Zintan.

A US F-15 jet crashed in rebel-held eastern Libya late on Monday following a malfunction as it took part in a raid against government anti-aircraft defences, but the two crew members ejected and were safe.

Admiral Samuel Locklear, commander aboard the USS Mount Whitney in the Mediterranean, said "one crew member was recovered by coalition forces. The other crew member was recovered by Libyan people. He was treated with dignity and respect, (and) is now in the care of the United States."

After a third night of strikes on Kadhafi's strongholds and defence structure, US Defence Secretary Robert Gates said "significant military fighting that has been going on should recede in the next few days."

Destroying radar and missiles under Kadhafi'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.

In Misrata, a rebel spokesman reached by telephone said insurgents remained in control despite an onslaught by Kadhafi loyalists who had opened fire with tanks and set snipers on roofs to gun down people in the streets.

A standoff persisted in eastern Libya, where Kadhafi forces in and around Ajdabiya, south of the insurgents' capital of Benghazi, easily repulsed attempts by the disorganised and ill-armed rebels to advance.

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.

US President Barack Obama, French President Nicolas Sarkozy and British Prime Minister David Cameron agreed that NATO should play a key role in the command structure of the Libya mission, the White House said.

"They reviewed the substantial progress that's been made in terms of halting the advance of Kadhafi's forces on Benghazi as well as the establishment of a no-fly zone," spokesman Ben Rhodes said.

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.

Juppe called for the creation of a special committee of foreign ministers from coalition countries to oversee operations, which he said should meet in the coming days "to show clearly that political oversight is there."

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.

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."

Russia and the United States clashed over Western bombing raids, with the US defence chief saying Moscow had accepted Moamer Kadhafi's "lies" about civilian casualties.

In talks with Gates, Russia's President Dmitry Medvedev voiced dismay over what he called the "indiscriminate use of force."

Gates rejected Moscow's criticism, even as he predicted that the bombing would be scaled back within days.

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 Obama and Turkey's Erdogan agreed to seek a "broad-based international effort, including Arab states."

Oil prices rose after dipping on profit-taking earlier in the day.

Brent North Sea crude for delivery in May rose 49 cents to $115.45 a barrel in late London trade, while New York's main contract, light sweet crude for April jumped $1.42 to $103.75.

And the United States placed sanctions on 14 firms controlled by Libya's National Oil Corp, tightening a financial noose on a key source of funds for the Kadhafi regime.

Meanwhile, it emerged that three western journalists who went missing in eastern Libya last week, including two from Agence France-Presse, were arrested by Kadhafi's forces on Saturday.

AFP chairman Emmanuel Hoog wrote to Kadhafi on Tuesday, asking that he free AFP's Dave Clark and Roberto Schmidt, and Joe Raedle from the Getty agency.

"I have the honour to ask you to restore their liberty, in the name of that same freedom of expression and information that you refer to so often," Hoog wrote.

Reporter Clark and photographer Schmidt, and Raedle, had not been heard from since Friday evening.

Their driver Mohammed Hamed told AFP 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.