The suspected use of chemical weapons in Syria demands an international response but NATO will not take part, alliance head Anders Fogh Rasmussen told Danish media on Friday.
"I see no NATO role in an international reaction to the (Syrian) regime," Rasmussen told reporters in the Danish town of Vejle, daily Politiken reported.
He said the alleged use of chemical weapons was "a terrifying and horrible act. Chemical attacks are a clear violation of international standards -- a crime that can't be ignored."
"It demands an international response, so it doesn't happen again," Rasmussen said.
The NATO secretary general has in the past insisted on the need for a political solution to the Syrian conflict.
UN inspectors have visited the scene of the August 21 suspected gas attack near the Syrian capital.
The opposition says more than 1,300 people died when toxic gases were unleashed on Eastern Ghouta and Moadamiyet al-Sham. Doctors Without Borders said 355 people died of "neurotoxic" symptoms in the affected areas.
Rasmussen said he firmly believed the Syrian regime was behind the attack.
"I have no doubt that the regime carried out a chemical attack," he said, adding: "When you look at who has the chemical stocks and the means to use them in an attack, you have to say that it is the regime."
"There's not much to suggest that the opposition would be in a position to carry out such an attack."