Story highlights At least six people have been killed Monday, according to opposition activists

The U.S. ambassador to NATO says the Syrian uprising is unlike Libya's

At least 60 people were killed across Syria on Sunday, opposition activists say

The U.S. ambassador to NATO says the alliance has no plans for military intervention in the Syrian crisis, as reports of deaths mount by the dozens and diplomatic efforts have yet to stymie the bloodshed.

Ivo Daalder told reporters late Sunday there is "no planning going on that's related to a NATO role in Syria."

"As it relates to NATO planning, a NATO ally has to come forward and request that type of planning. So that's a circumstance that hasn't taken place," the ambassador said. "We'd obviously take any requests of that nature seriously if it were to be made."

Daalder also said that NATO, along with European allies and Arab partners, has provided assistance to the Syrian opposition, including political and diplomatic support.

"We've also decided, however, that a military intervention of the nature that we did in Libya would further militarize the situation in ways that wouldn't necessarily protect civilian life," Daalder said. "... Unlike Libya, you don't have pockets of the country that can be protected by civilian protection zones. You've got security forces intermingled with the population, and that introduction of greater military intervention from outside or arms to groups within Syria could further militarize the conflict in a counterproductive way."

On the same day Daalder spoke, at least 60 people were killed in Syria's 14-month crisis, opposition activists said.

Among the dead, at least 40 were killed in the northwestern city of Hama, where a neighborhood sustained heavy shelling by government troops, said the Local Coordination Committees of Syria, a network of opposition activists.

On Monday, activists said, six people died across the country. The deaths included three unidentified bodies.

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The United Nations says at least 9,000 people have been killed since initially peaceful protests against President Bashar al-Assad erupted in March 2011. Opposition activists put the toll at more than 11,000.

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Syria's government, meanwhile, said it buried 18 more members of its security forces who died battling "armed terrorist groups" around the country. CNN cannot independently verify reports of deaths and violence because the Syrian government has severely restricted access by international media.

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The fighting has continued despite a peace plan brokered by former U.N. Secretary-General Kofi Annan, now a special envoy for the United Nations and the Arab League.