Calls for more contribution from allies were repeatedly heard during the Berlin session, and Rasmussen told reporters that the alliance is in need of several precision fight aircraft and sophisticated equipment at the moment.

He said Gaddafi' forces has changed tactics and hidden heavy arms in highly-populated areas. To avoid possible civilian casualties, NATO has to make precision attacks.

Although Rasmussen said he was confident that the alliance would "step up to the plate," the NATO chief did not announce any specific pledges or promises during the two-day meeting, simply saying that he "heard indications that gave me hope."

Rasmussen said in several occasions that the Berlin meeting has "a very positive discussion and a clear expression of unity of purpose and resolve." However, even before the meeting, signs of discord have emerged as France and Britain impatiently pressed their allies to make more robust contribution for the ongoing mission in Libya, where three weeks of air strikes failed to help the rebels gain the upper hand in the battle field against government troops.

A French official said earlier that Italy, Spain, the Netherlands and Sweden should do more for the joint mission. But Spain government responded Thursday that it had no plan to take part in any air strikes.

Another vital player, the United States also did not say if it would send more jets in Berlin. U.S. Secretary of State Hillary Clinton stressed that the NATO members are "sharing the same goal" and "contributing in many ways to see that goal realized", avoiding discussion on new pledges and downplaying divisions within the alliance.

"As our mission continues, maintaining our resolve and unity only grows more important," she added. Washington handed over the control and command to NATO on March 31, but it still assumed one third of flying missions.

On the first meeting of the Contact Group on Libya this week in Doha, countries discussed on whether the international community could provide the rebel army with arms for counter attack government troops or for self defense.

NATO members differ on this issue. Italy was in favor of the suggestion, but collected few positive response. As NATO's mission should be in accordance with UN Security Council Resolution 1973, which request an arms embargo to Libya, sending weapons to rebels would violate the rules of the resolution.

"As regards to arms, we have been mandated by the UN Security Council to enforce an arms embargo and we will do so in strict conformity," Rasmussen said, adding that he received no request of amending the resolution in the meeting.

Analysts said that in coming months, NATO's resolve and coordination capability would be put to serious test as the two conflicting sides in Libya came into a seesaw battle, with Qaddafi' s force controlling the west and rebels the east.

NATO has apparently been aware of that. Answering questions of German magazine Spiegel, Rasmussen said that "the worst outcome would be a military stalemate or a de facto partition of Libyan society, in which Libya would become a failed state and a breeding ground for terrorist groups -- and that so close to Europe's borders."