Abdeltawwab Shahrour, head of the forensic medicine committee in Aleppo, claims there was a chemical attack in Khan al-Assal, Aleppo, on March 19, Istanbul-based opposition coalition spokeswoman Sarah Karkour said.
A second official said that Shahrour, who has defected to Turkey, has documents proving the attack took place.
According to Sky News, both the Assad government and rebels have blamed each other for an attack in which chemical weapons were alleged used.
The report said that Russia, which along with Iran is Syria's closest ally and chief arms supplier, said in July its own scientific analysis indicated the attack had involved the nerve agent sarin.
Russia said that the attack was most likely been carried out by the rebels.
Dr Shahrour was expected to reveal the details of the attack during a press conference in Turkey, but Syrian National Council spokesperson Khaled Saleh said he was unable to appear due to security concerns, the report added.
--ANI (Posted on 04-09-2013)