Brussels - NATO's chief urged the UN on Thursday to quickly act on Libya to stop Muammar Gaddafi from crushing rebels, but the alliance was divided even as it pressed ahead with plans for a no-fly zone.
"If Kadhafi prevails it will send a clear signal that violence pays. That would be unacceptable from a humanitarian and democratic perspective," Secretary General Anders Fogh Rasmussen said.
"But time is running out. The sooner the United Nations can reach an agreement the better," he said on his Facebook page.
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 Kadhafi from using his air force to bomb his population.
Russia, Germany and other countries of the 15-member Security Council have expressed opposition or doubts about military action in Libya.
"I can't imagine the international community and the United Nations will stand idly by if the Libyan regime continues to attack its own civilian population systematically," Rasmussen told reporters during a visit in Warsaw.
He said attacks by Gaddafi's regime on civilians "may amount to crimes against humanity."
NATO military officials presented to ambassadors this week a range of plans for a potential role in Libya, including assisting humanitarian relief efforts, enforcing an arms embargo and grounding the Libyan air force, diplomats said.
"NATO stands ready to protect the civilian population if there is a demonstrable need, clear legal basis and strong regional support," Rasmussen said.
But divisions exist within the 28-nation alliance as well, with Germany and Turkey voicing opposition to a military intervention.
In addition, France, which has taken a hawkish stance in the Libyan crisis, "does not want NATO in the front line," a NATO military official said.
This could leave NATO, already with its hands full leading the war in Afghanistan, on the sidelines in a no-fly zone in Libya.
France and Britain, which has also led clarion calls for a no-fly zone, could end up taking action outside the NATO club alongside Arab nations.
The United States has also shown "little enthusiasm" in trying to bring Turkey and Germany in line with the rest of the alliance, the military official said.
The official said the Americans believe that a no-fly zone would not be enough to defeat Gaddafi, and that ground troops would be needed, an option the United States would not take part in given its commitments in Iraq and Afghanistan.
US ambassador to the United Nations Susan Rice suggested as much on Wednesday, saying that action might have to "go beyond a no-fly zone at this point, as the situation on the ground has evolved, and as a no-fly zone has inherent limitations in terms of protection of civilians at immediate risk."
NATO ambassadors could meet again Friday and this weekend to review the alliance's contingency plans for Libya and decide the next steps, diplomats said.
"NATO wants these operational plans to be ready by the end of the week or early next week," an alliance diplomat told AFP on condition of anonymity because of the sensitivity of the planning.
The alliance "is accelerating the preparations, but no green light has been given," the diplomat said.
Even if the UN approves a no-fly zone and all allies agree to back the move, it would take two weeks for NATO to be operational, the NATO military official said, adding: "The chances that NATO will have a role are minimal."