BRUSSELS — Any use of chemical weapons by Syria's government would prompt an immediate international response, NATO's chief warned on Tuesday, saying the chemical threat made it urgent for the alliance to send Patriot missiles to Turkey.

International concern over Syria's intentions has been heightened by media reports that its chemical weapons have been moved and could be prepared for use in response to dramatic gains by rebels fighting to topple President Bashar al-Assad.

"The Syrian stockpiles of chemical weapons are a matter of great concern. We know that Syria possesses missiles, we know they have chemical weapons and of course that also has to be included in our calculations," NATO Secretary-General Anders Fogh Rasmussen told reporters at the start of a meeting of alliance foreign ministers in Brussels.

"This is also the reason why it's a matter of urgency to ensure effective defence and protection of our ally Turkey," he said. "The possible use of chemical weapons would be completely unacceptable for the whole international community and if anybody resorts to these terrible weapons I would expect an immediate reaction from the international community."

Rasmussen was echoing U.S. warnings that any attempt by the Syrian government to use chemical weapons against the rebels would be a "red line" that would prompt U.S. action.

Syria said on Monday that it would not use chemical weapons against its own people.