"If Qadhafi prevails it will send a clear signal that violence pays. That would be unacceptable from a humanitarian and democratic perspective," Rasmussen said on his Facebook page.

"But time is running out. The sooner the United Nations can reach an agreement the better," he said.

"NATO stands ready to protect the civilian population if there is a demonstrable need, clear legal basis and strong regional support."

Speaking to reporters during a visit to Poland, Rasmussen said that attacks by Qadhafi's regime on civilians "may amount to crimes against humanity."

He said: "It is absolutely outrageous to see the Libyan regime systematically attack its own civilian population."

France, Britain and the United States are pressing for a UN Security Council vote Thursday on a resolution that includes a no-fly zone to prevent Qadfhafi from using his air force to bomb rebels.

Russia, Germany and other countries of the 15-member Security Council have expressed opposition or doubts about military action in Libya.

NATO military officials have drafted a range of plans for a possible role in Libya, including the enforcement of a no-fly zone.

But divisions exist within the 28-nation alliance, with Germany and Turkey voicing opposition to any military intervention in Libya, which could leave NATO on the sidelines in any no-fly zone.

In addition, France, which has taken a hawkish stance in the Libyan crisis, would prefer if NATO stayed out of Libya, a NATO military official said.