As well as Britain and France, Denmark and Canada said they would supply fighter jets for the mission. Italy and Spain said they would make their air bases available.
Diplomats have said Arab countries likely to participate in possible strikes include Saudi Arabia, Qatar, the United Arab Emirates and Jordan.
NATO surveillance AWACS planes flying off the Libyan coast are already providing 24-hour coverage of the situation in the air and on the battlefields. Analysts said no-fly zone aircraft would be flying from NATO bases such as in Sigonella, Sicily, Aviano in northern Italy, Istres in southern France, and Ventiseri-Solenzara in Corsica.
The North Atlantic Council, NATO's top decision-making body, decided Friday to speed up planning and will meet again in the next few days when plans are complete, an alliance spokeswoman said, speaking on condition of anonymity because of the delicacy of the situation.
Envoys said there was no discussion at the NATO meeting of any air strikes against targets in Libya.
Even as allies made plans for military intervention, Libya's cease-fire was forcing a reassessment of the situation.
"Along with our colleagues we're looking at the details of that," the EU's high representative for foreign affairs, Catherine Ashton, said of the cease-fire, adding that it was unclear what Libyan Foreign Minister Moussa Koussa's announcements in Tripoli meant in practice.
Chancellor Angela Merkel of Germany — which abstained from the Security Council vote — said the international community would monitor closely to make sure the cease-fire announcement is not a ruse.
"The international community stands together and there are already encouraging reports that Gadhafi is reacting to the resolution," Merkel told reporters in Berlin.
There are also mixed messages about the ultimate ambition of a no-fly zone. Cameron insisted the aim is saving lives, not regime change, but Clinton said the goal remained to get rid of Gadhafi.