As US warships entered the Mediterranean Wednesday, NATO allies were divided on whether to use military might in Libya while Moamer Kadhafi warned that any Western foray would leave thousands dead, AFP reports.

The United States and Britain have raised the possibility of creating a no-fly zone to prevent Kadhafi from launching air raids on his people, with London claiming that a UN mandate was not necessarily needed.

Warning that military action could turn Arabs against Europe, French Foreign Minister Alain Juppe insisted that any operation, including policing Libya's skies, would first need approval from the United Nations.

"Should we prepare for a military intervention? We don't think so in this context," he told the French National Assembly.

In Cairo later, the Arab League said it would consider backing a no-fly zone but ruled out support for direct foreign military intervention in the country.

"The Arab countries cannot remain with their arms folded when the blood of the brotherly Libyan people is being shed," the league said in a resolution after a meeting of foreign ministers in Cairo.

"The ministers have decided to pursue talks on the best way to protect Libya's citizens and to assure their security, including the imposition of an aerial exclusion zone and coordination between the Arab League and the African Union on this subject," it said.

The French government expressed its "reluctance" at a meeting of ambassadors of the 28-nation alliance in Brussels, Juppe said, adding however that planning for a possible no-fly zone should continue in case the UN approves one.

British Deputy Prime Minister Nick Clegg, during a visit to EU headquarters, said Britain would not enforce a no-fly zone on its own "but we think essential to plan for every contingency."

A NATO diplomat said allies were making contingency plans in case the UN asks the alliance to act in Libya.

As Kadhafi's forces launched raids against the opposition, with warplanes reportedly launching air strikes in two eastern towns, NATO's decision-making body, the North Atlantic Council, met in Brussels.

Ambassadors "discussed the fast-moving situation in Libya" and expressed "great concern about continued violence and also about the serious humanitarian situation," NATO deputy spokeswoman Carmen Romero told AFP.

"The alliance continues to actively monitor events in that country," she said.

NATO Secretary General Anders Fogh Rasmussen continues to consult with international partners "in order to be prepared to assist in any eventuality if requested to do so," she said, refusing to elaborate.

US Defence Secretary Robert Gates has acknowledged that there was no unanimity within NATO for the use of force.

Turkey, an influential NATO member with a majority Muslim population, rejected the idea of military action, saying the alliance could only intervene when one of its members is attacked.

"This would be absurd," Turkish Prime Minister Recep Tayyip Erdogan said during a visit in Germany this week, according to Anatolia news agency. "NATO has no business being there."

"We are opposed to such a scenario. Such an eventuality is unthinkable."

The United States flexed its military muscle Wednesday as two US warships carrying marines and equipment steamed into the Mediterranean Sea en route to Libya.

Holed up in Tripoli, Kadhafi warned that Western intervention to help rebels would trigger a "very bloody war" in which "thousands of Libyans would die."

The US military warned that enforcing a no-fly zone would be a complex operation that would require bombing the Kadhafi regime's radar and missile defences.

During a meeting with EU foreign policy chief Catherine Ashton on Tuesday, NATO's Rasmussen said an aerial mission over Libya would be complicated because of humanitarian operations on the ground, a European diplomat said.

Backed by US military firepower, NATO has a vast list of assets available to undertake a complex mission.

Germany hosts a fleet of AWACS, large radar and surveillance aircraft that can monitor the skies, while US bases in Italy could serve as a staging area for operations.

The military alliance enforced a UN-mandated no-fly zone once before in Bosnia during the Balkans war in the early 1990s.

Winning a UN mandate for Libya could prove difficult, with the foreign minister of Russia, a veto-wielding member of the Security Council, dismissing talk of a no-fly zone as "superfluous."