The concern is not only that the Syrian regime may use chemical weapons, but that they could fall into the hands of terrorist groups.
The Syrian foreign ministry on Saturday reiterated its position that it will not use chemical weapons, if it possesses any, under any circumstances, the state news agency SANA reported.
In two letters addressed to the U.N. Security Council and the U.S. Secretary-General, the ministry warned that "terrorist groups might resort to using chemical weapons against the Syrian people... after the terrorist groups recently took hold of a chlorine processing plant to the east of Aleppo city," according to SANA.
The Syrian government commonly refers to anti-government rebels as "terrorists."
"Syria is defending its people against terrorism supported by known countries, above all (the) USA," the ministry wrote.
The Free Syrian Army rejected any claim that it could have or use chemical weapons. "We do not plan, own, or have the capability to use chemical weapons against our own people," said political and media coordinator Louay Almokdad.
Another view on weapons
Fears of chemical weapons use by the Syrian government are "hysterical hype," former U.S. National Security Adviser Zbigniew Brzezinski said Saturday.
Speaking with CNN's Randi Kaye, Brzezinski said it does not make sense that the Syrian regime would employ such weapons when doing so would in effect poison its own people.
The fighting in Syria is not along traditional fronts, but sporadic outbreaks of fighting, making chemical weapons not very effective, he said.
"It's more like a guerrilla warfare. How do you use chemical weapons against that," he said.
The real challenge, Brzezinski said, is creating a stable situation in Syria so the conflict does not spill into Jordan, Lebanon or Iraq.