Syrian rebels have opened a new front in Aleppo as fighting spread on the third day of a major insurgent counter-attack to break the government's siege of the opposition-held part of the city, with each side accusing the other of using poison gas.
The rebels, including both Free Syrian Army factions and jihadists, are seeking to end the siege by seizing government-held areas of the city, in an effort to link the rebel-held east with rural areas to the west of the city.
Syrian state media said militants had fired shells containing chlorine gas at a residential area of the government-held western part of the city, al-Hamdaniya.
Rebels denied that, and said government forces had fired poison gas on another frontline.
State media cited an Aleppo hospital director saying three dozen people - civilians and soldiers - had suffered suffocation in the alleged rebel gas attack, but did not report any deaths.
The Syrian Observatory for Human Rights, a UK-based organisation that reports on the war, said it had confirmed reports of suffocation among government fighters in two frontline areas shelled by rebels, but it did not know if chlorine gas was the cause.
The rebels said the army had shelled rebel-held Rashideen district with chlorine and shared videos purportedly showing victims with respiratory problems.
Aleppo, Syria's biggest pre-war city, has become the main stage of conflict between President Bashar al-Assad, backed by Iran, Russia and Shia militias, and Sunni rebels including some supported by Turkey, Gulf monarchies and the United States.
