Syria's foreign ministry has said it will only use chemical weapons if it faces "external aggression", but would not use them against its civilians.
A spokesperson said the weapons were guarded by the Syrian army and said the security situation in Damascus was improving.
It appeared to be the first time that Syria acknowledged it might possess non-conventional weapons.
Syria is not a signatory to the 1992 Chemical Weapons Convention that bans their use, production or stockpiling.
A spokesman raised the possibility that "terrorists groups" might be supplied with biological weapons by outside powers, which "could be used in one of the villages - God forbid - and then they would accuse the Syrian forces".
He also said the security situation in Damascus, where President Bashar al-Assad's forces have been battling rebels for more than a week, was improving and would return to normal within days.
The spokesman condemned calls for Mr Assad to step down at a meeting of Arab foreign ministers in Qatar over the weekend, saying it was a "flagrant intervention" in Syria's internal affairs.
UN Secretary-General Ban Ki-moon has said he is concerned about the risk of Syria using chemical weapons.
"It would be reprehensible if anyone in Syria would use weapons of mass destruction," Mr Ban told reporters during a visit to Serbia.
'Tragic mistake' to use chemical weapons
US President Barack Obama said that President Assad would be held accountable if he made the "tragic mistake" of using his stockpile of chemical weapons.
"Today we're also working so that the Syrian people can have a better future, free of the Assad regime," said Mr Obama.
"Given the regime's stockpiles of chemical weapons, we will continue to make it clear to Assad and those around him that the world is watching and that they will be held accountable by the international community and the United States should they make the tragic mistake of using those weapons."
Elsewhere, Syrian troops drove rebel fighters out of two districts of Damascus a week after insurgents launched a major assault on the capital and killed four of the president's closest associates in a bomb attack last Wednesday.
Government troops retook control of the Damascus neighbourhood of Mezzeh yesterday.
Opposition activists said the troops executed at least 20 unarmed men who they suspected of aiding rebels.
Reports from Syria cannot be independently verified due to state restrictions on foreign media.
In a further escalation of the conflict, fighting raged around the intelligence headquarters in Syria's biggest city, Aleppo, and in Deir al-Zor in the east.
Syrian forces said they had regained control of one of two border crossings seized by rebels on the frontier with Iraq.
But rebels said they had captured a third border crossing with Turkey - at Bab al-Salam, north of Aleppo.
Elsewhere, Iraqi officials said Syrian forces had regained control of the Syrian side of the Yarubiya border crossing, briefly seized by rebels on Saturday.
Iraq had said it cannot help Syrians fleeing the violence, and the border was sealed by the Iraqi army on Friday.
However, Iraqi Prime Minister Nuri al-Maliki today told Iraq's border officials to allow Syrian refugees into the county, a senior border commander said.
General Issam Yassim was speaking to Reuters at Iraq's southern Al-Waleed border crossing with Syria, 560km west of Baghdad.
He said it applied to all Iraqi border crossings with Syria.
Meanwhile, Turkey has recalled its consul from Aleppo, after the battles between insurgents and President Assad's forces.
Children deliberately targeted in Syria - War Child
A UK-based group has said no child is safe from the bloody conflict in Syria amid reports of a "shocking" scale of brutality against children.
War Child is providing emergency assistance to Syrian child refugees in Lebanon.
The group said young Syrians were being deliberately murdered in execution-style killings, raped, abused, used as human shields and even enlisted against their will to fight.
A report has said the Syrian conflict was "disturbingly unique" in its deliberate targeting of children, warning that no child is now safe.
War Child is urging the international community to step up efforts to protect children caught up in the fighting.
It said it believed between 500 and 1,300 children had been killed, while eight-year-olds were being enlisted as soldiers.
The report said both girls and boys have been sexually abused and more than 600 children have been placed in detention centres where torture is commonplace.
It also claims 49 children were massacred in one incident.
War Child Chief Executive Rob Williams said: "The Syrian conflict must now rank as one of the worst for the depth and scale of abuses against children."
Mr Williams claimed that "when adults go to war they have a legal duty to protect children yet neither side is protecting children in the areas they control".
Minister of State for European Affairs Lucinda Creighton has said that EU foreign ministers believe that the end of Assad regime in Syria is getting closer.
Speaking in Brussels, she said the European Union had to prepare for that eventuality.
Ms Creighton, who was standing in for Tánaiste Eamon Gilmore at EU Foreign Affairs Council, said that forging a coherent partner in Syria would be really difficult and really challenging.
She added that some groups in the Syrian opposition would not be desirable partners for the EU.
