If confirmed, it would be the first use of such weapons in the two-year-old conflict.
Syria’s information minister al-Zoubi said rebels had fired a rocket carrying chemical agents that killed 25 people and injured over 100.
The minister blamed ‘terrorists’ for firing a rocket with chemical substances in al-Neirab on Khan al-Asal in Aleppo in what he called a “dangerous escalation” and held the countries that are arming syria’s opposition responsible for the attack in Aleppo.
Meanwhile, Russia’s ministry said in a statement: “This incident constitutes a very worrying and serious development in the context of the crisis in Syria.”
However, a Free Syrian Army commander denied media reports on Tuesday that opposition forces were behind the chemical weapon attack in Aleppo, accusing the regime, according to AP.
The Syrian Observatory for Human Rights, an opposition group, put the number of dead at 26, including 16 regime soldiers.
President Bashar Assad, battling a two-year-old uprising against his rule, is widely believed to have a chemical arsenal.
Syrian officials have warned that if it existed it would be used to defend against foreign aggression, not against Syrians.
Meanwhile, the White House says it has no evidence to back up Bashar Assad’s claim that Syrian rebels have used chemical weapons.
US President Barack Obama, has previously warned Assad that any use of chemical weapons would be a “red line”.
On ground, Syrian rebels on Tuesday seized a guard post near the Jordanian border and a tank brigade headquarters in the south of the country, after regime forces withdrew, the Syrian observatory for Human Rights reported, according to Al Arabiya.