[attach id=242745 size="medium"]A tank belonging to forces loyal to Syria’s President Bashar al-Assad is set on fire during what activists said were clashes between government forces and the Free Syrian Army, in the main south highway near Damascus, yesterday. Photo: Mohammed Dimashkia/Reuters[/attach]

Syria’s government and rebels accused each other of launching a deadly chemical attack near the northern city of Aleppo yesterday in what would, if confirmed, be the first in the two-year conflict.

US President Barack Obama, who has resisted overt military intervention in Syria, has warned President Bashar al-Assad that any use of chemical weapons would be a “red line”.

There has, however, been no suggestion of rebels possessing such arms.

Syria’s state television said rebels fired a rocket carrying chemical agents that killed 25 people and wounded dozens. The pro-opposition Syrian Observatory for Human Rights, which monitors the conflict, said 16 soldiers were among the dead.

The most notorious use of chemical weapons in the Middle East in recent history was in the Iraqi Kurdish city of Halabja where an estimated 5,000 people died in a poison gas attack ordered by former Iraqi President Saddam Hussein 25 years ago.

No Western governments or international organisations confirmed a chemical attack in Syria, but Russia, an ally of Damascus, accused rebels of carrying out such a strike.

Syria’s Deputy Foreign Minister, Faisal Meqdad, said his government would send a letter to the UN Security Council “calling on it to handle its responsibilities and clarify a limit to these crimes of terrorism and those that support it inside Syrian Arab Republic”.

He warned that the violence that had engulfed Syria was a regional threat. “This is rather a starting point from which (the danger) will spread to the entire region, if not the entire world,” he said.

The United States said it had no evidence to substantiate charges that the rebels had used chemical weapons.

UN spokesman Martin Nesirky said it was not in a position to confirm the reports, adding that if either side used such weapons it would be a “grave violation of international law”.

Britain said its calculations would change if a chemical attack had taken place. A Foreign Office spokeswoman said it would “demand a serious response from the international community and force us to revisit our approach so far”.

Such an attack would demand a serious response from the international community

A Reuters photographer said victims he had visited in Aleppo were suffering breathing problems and said they could smell chlorine after the attack.

“I saw mostly women and children,” said the photographer, who cannot be named for his own safety.

He quoted victims at the University of Aleppo hospital and the al-Rajaa hospital as saying people were dying in the streets and in their houses.

The revolt against four decades of family rule started with peaceful protests two years ago but descended into a civil war after Assad’s forces shot and arrested thousands of activists and the opposition turned to armed insurgency.

Assad is widely believed to have a chemical weapons arsenal. Syrian officials have neither confirmed nor denied this, but have said that if it existed it would be used to defend against foreign aggression, not against Syrians. There have been no previous reports of chemical weapons in the hands of insurgents.

Information Minister Omran al-Zoabi said rebels fired “a rocket containing poison gases” at the town of Khan al-Assal, southwest of Aleppo, from the city’s southeastern district of Nairab, part of which is rebel-held. “The substance in the rocket causes unconsciousness, then convulsions, then death,” the minister said.

But a senior rebel commander, Qassim Saadeddine, who is also a spokesman for the Higher Military Council in Aleppo, denied this, blaming Assad’s forces for the alleged chemical strike. “We were hearing reports from early this morning about a regime attack on Khan al-Assal, and we believe they fired a Scud with chemical agents,” he told Reuters by telephone from Aleppo.

Meanwhile, Turkish Prime Minister Tayyip Erdogan rejected an accusation from Syria yesterday that Turkey bore responsibility for a possible chemical attack in the northern province of Aleppo.

“Turkey has never been in a situation in which it used chemical weapons. There are no chemical weapons in our inventory,” Erdogan told reporters.