DAMASCUS: Syria warned the United Nations on Saturday that rebels may use chemical weapons after they gained control of a factory producing toxic chlorine east of Aleppo city.

"Terrorist groups may resort to using chemical weapons against the Syrian people... after having gained control of a toxic chlorine factory," the foreign ministry said, adding that Syria would never use chemical weapons.

The statement may be referring to the Syrian-Saudi Chemicals Company (SYSACCO) factory near the town of Safira, which was taken over earlier this week by rebel fighters from the jihadist Al-Nusra Front.

This factory, which produces sodium hydroxide and hydrogen chloride, is in an agricultural area and has been the subject of numerous complaints from farmers for polluting the local water supply.

The ministry sent separate letters to the UN Security Council and UN Secretary General Ban Ki-moon, reiterating that Syria would "not use chemical weapons under any circumstance, if they exist."

Syria "is defending its people against terrorism, which is supported by known countries, with the United States at the forefront," it added.