CBRN event in Syrian Arab Republic on Tue 19th March 2013

Syrian rebels and the government have accused each other of firing chemical weapons, reportedly killing at least 25 people in the north of the country. 

A Syrian minister said it was a "dangerous escalation" and the "first act" of a new rebel authority.

However, both a chemical weapons monitoring body and the US said there was no evidence they had been used.

Both sides say the attack happened in the Khan al-Assal region north of the second city, Aleppo.

The US says it is looking carefully at the allegations, while Russia has backed the Syrian government's claims.

If confirmed, it would be the first time chemical weapons have been used in the two-year Syrian conflict.

"Terrorists launched a missile containing chemical products into the region of Khan al-Assal in the province of Aleppo, killing 15 people, mainly civilians," Sana news agency said.

The government routinely refers to rebels as "terrorists".

State TV later said 25 people had died, while the pro-opposition Syrian Observatory for Human Rights put the figure at 26, including 16 soldiers.

Senior rebel and spokesman for the Higher Military Council in Aleppo Qassim Saadeddine said the government had carried out a chemical attack.

"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 news agency.

"Then suddenly we learned that the regime was turning these reports against us. The rebels were not behind this attack."

The Aleppo Media Centre, which is affiliated to the rebels, said there had been cases of "suffocation and poison'' among civilians in Khan al-Assal after a surface-to-surface missile was fired at the area.

It said this was "most likely" due to use of "poisonous gases" by government forces.

Ahmet Uzumcu, director general of the Organization for the Prohibition of Chemical Weapons (OPCW), said it was trying "to identify the symptoms which may be detected" in order to make an assessment.

He said he had no more information than what was in the media, Reuters reports.