NATO on Tuesday approved member state Turkey's request for Patriot missiles to defend its border against Syria following a series of blunt warnings to Damascus not to use chemical weapons.

As the conflict approached the 21-month mark with more than 41,000 people killed, according to the Britain-based Syrian Observatory for Human Rights, NATO head Anders Fogh Rasmussen said the alliance's decision reflected a "steadfast commitment" to preserving the security of its 28 member states.

"We say to anyone who would want to attack Turkey -- don't even think about it," he remarked, announcing the decision after the first day of a two-day meeting in Brussels.

NATO said in a statement that it had "agreed to augment Turkey's air defence capabilities in order to defend the population and territory of Turkey and to contribute to the de-escalation of the crisis along the alliance's border."

Germany, the Netherlands and the United States have agreed to provide the Patriot missile batteries, which would come under the command of the Supreme Allied Commander Europe (SACEUR), the statement said.

Stressing that the Patriot system was purely defensive, Rasmussen said technical discussions would now follow about how many of the US-made Patriots would be deployed and where.

The NATO discussions came amid reports that Syria is moving chemical weapons as President Bashar al-Assad fights rebels seeking to oust him.

"NATO members expressed grave concerns about reports that the Syrian regime is considering the use of chemical weapons. Any such action would be completely unacceptable and a clear breach of international law," Rasmussen said.

Earlier, Rasmussen said he would "expect an immediate reaction from the international community" if Damascus were to use such weapons.

On Monday, US President Barack Obama warned Assad against using chemical weapons, saying there would be "consequences" for such an action.

France said it would take a "very strong position" against any chemical weapons use, though Foreign Minister Laurent Fabius stressed that reports on Syria moving its chemical arms stocks "have not been verified or confirmed".

Confirmation of a Syrian chemical weapons threat "would demand an immediate reaction from the international community", Fabius said.

Israeli Prime Minister Benjamin Netanyahu said Israel was also closely following the chemical weapons issue and sees things "the same way" as its ally, the United States.

"We believe these weapons must not be used and must not fall into the hands of terrorist elements," Netanyahu said.

Turkey welcomed NATO's decision, and reiterated that the weapons are solely for defensive purposes.

"The measures that will be taken by Turkey will in no case be used for offensive operations. This system is only slated for the defence of Turkish territory," the Turkish foreign ministry said in a statement.

It added that the US-made surface-to-air missiles will not in "any way be used to promote an air exclusion zone" over neighbouring Syria.

Turkey's request for the missiles has worried Russia, a longtime ally of Syria that is deeply suspicious of NATO's motives.

After NATO talks with Russian Foreign Minister Sergei Lavrov earlier Tuesday, Rasmussen had said deploying Patriots would be "an effective deterrent and in that way de-escalate the situation" along the border.

Lavrov dismissed that point, saying the chemical weapons issue was overblown while the Patriot deployment created "the risk that these arms will be used".

It was not the first time there were such "rumours and leaks" about chemical weapons and they should "not be overstated", he said, while reaffirming Moscow's position that any use of chemical arms would be a violation of international treaties.

The Syrian government, fighting to prevent the capital Damascus from falling to rebel forces, has said it will never resort to chemical weapons.

On the ground Tuesday, the Syrian army blasted a string of rebel zones on the eastern and southwestern outskirts of Damascus.

Rami Abdel Rahman, director of the Syrian Observatory for Human Rights, said "the army is trying at all costs to keep the rebels out of Damascus.

"The rebels are pushing hard to enter into the city but they have not been able to make the advance they are hoping for," he added.

Pro-regime daily Al-Watan reported that the army is "making progress in all directions in Damascus province, chiefly in villages along the road linking the capital to the international airport."

Syrian state television meanwhile reported that a rebel attack on a school near Damascus on Tuesday killed nine students and their teacher.

The Observatory said at least 102 people were killed in violence across Syria on Tuesday -- 44 civilians, 31 soldiers and 27 rebels.

In New York, officials from the UN's World Food Program said food rations for hundreds of thousands of people in need in Syria had to be cut due to cash shortages.

"We will see more cuts if we don't get the necessary funding," said Abeer Etefa, a spokeswoman for the food agency.

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