Syria is capable of using chemical weapons, a leading opposition leader warned on Monday after President Bashar al-Assad's regime said it could do so against "external aggression."

Abdel Basset Sayda accused certain Kurdish groups in the north of Syria of collaborating with President Bashar al-Assad.

"A regime that massacres children, that rapes women, can just as well use chemical weapons," the Anatolia news agency quoted Sayda, the chief of the Syrian National Council (SNC), as saying.

The statement came after a Syrian foreign ministry spokesman warned Syria would use chemical weapons if attacked by outsiders.

"Syria will not use any chemical or other unconventional weapons against its civilians, and will only use them in case of external aggression," Jihad Makdissi told reporters.

Sayda, speaking after a meeting with Turkey's Foreign Minister Ahmet Davutoglu, called on the international community to ensure that the weapons were never used, the agency reported.

The warning from the Damascus regime has already received a harsh response from the United States. UN chief Ban Ki-Moon also condemned any use of such weapons.

Sayda accused certain Kurdish groups in northern Syria close to the Kurdistan Workers' Party (PKK) of working with Assad's forces.

"The Syrian regime has entrusted this region to the PKK or to the PYD (Democratic Union Party) and has pulled out," said Sayda, who is a Kurd himself.

But the Kurdish people did not support these groups, he said: "They are on the side of the revolution."

The PKK, listed as a terrorist group by Turkey and much of the international community, took up arms in 1984, sparking a conflict that has claimed some 45,000 lives.

Some critics of the PYD consider it to be the Syrian branch of the PKK.

Kurds make up nearly nine percent of Syria's 23 million people.

EU ministers slam 'monstrous' Syria chemical weapons threat
Brussels (AFP) July 23, 2012 - European Union foreign ministers branded as "monstrous" and "unacceptable" a threat by Syria on Monday that it would resort to the use of chemical weapons in case of a foreign attack.

"Threatening to use chemical weapons is monstrous," said German Foreign Minister Guido Westerwelle in a statement.

"It is unacceptable to say they would use chemical weapons under any circumstances," echoed British Foreign Secretary William Hague.

In a statement issued after talks, the bloc's 27 foreign ministers said: "The EU is seriously concerned about the potential use of chemical weapons in Syria."

Syria denied the regime would ever use chemical or unconventional weapons against civilians, but admitted it would resort to their use "in case of external aggression."

"Any stocks of chemical weapons that may exist, will never, ever be used against the Syrian people," Syrian foreign ministry spokesman Jihad Makdissi said.

But he added that in the event of foreign attack, "the generals will be deciding when and how we use them."

The comments came as Syrian troops were battling rebels in the main cities of Damascus and Aleppo in the escalating conflict that activists say has claimed 19,000 lives since March 2011.

"The Syrian regime has once again revealed the contempt for human life in its thinking," added Westerwelle. "I urge all authorities in Syria to responsibly contribute to securing any chemical weapons stockpiles."

"What is actually happening is their own people are rising up against a brutal police state," said Hague.

"It has nothing to do with any agression from anywhere else in the world ... The sooner it comes to an end, the better."

EU foreign policy chief Catherine Ashton, who chaired the ministers' talks, said the existence of chemical weapons in any area of conflict was "cause of concern."

But asked to comment at a news conference, she added: "As far as I am aware, there is no reason to have immediate concern."

"But information is difficult to obtain," she said.

France was keeping a close eye on such weapons, however, said Foreign Minister Laurent Fabius.

"These installations are the object of very particular surveillance," he said.