Warplanes struck rebel positions in Aleppo’s countryside on Sunday, hours after the Syrian government accused rebels of launching a poison gas attack, according to the Syrian Observatory for Human Rights. The air raids are the first since Russia and Turkey agreed in September to create a demilitarised zone in adjacent Idlib to prevent a full-scale government offensive on Syria's last rebel-held province. Russia's defense ministry says its warplanes were behind the strikes. There were no immediate reports of casualties. Earlier on Sunday, state-run news agency Sana reported that 107 people were injured, including children, after rebels hit three government-held districts in Aleppo with projectiles containing gases that caused choking. It marks the highest such casualty toll in Aleppo since government forces and their allies clawed back the city from rebels nearly two years ago. A Syrian doctor at the Aleppo University Hospital said patients he treated were discharged less than two hours after being admitted, noting that they only displayed mild symptoms. Dr Mahmoud Sweig told <em>The National</em> that hospital staff treated at least 85 patients for gas poisoning. He said the symptoms included red eyes, heart palpitations and difficulty breathing. It remains unclear what type of poison gas was used, Dr Sweig said, but noted that his team had not detected any sign of substances like sarin or phosphorous. He said that most patients were discharged within a couple of hours after being instructed to dispose of their clothes. He clarified that no one had died as a result of the suspected gas attack. “The ER was filled to capacity; we had patients coming in every two minutes,” Dr Sweig said. “We were scared it was phosphorous – but there was no nerve damage or slowing of the heart,” he said. Russian Defense Ministry spokesman Maj. Gen. Igor Konashenkov said Russian chemical weapons specialists have been dispatched to Aleppo. "According to preliminary data, particularly the symptoms shown by the victims, the shells that bombarded residential areas of Aleppo were filled with chlorine gas," Mr Konashenkov said. Syrian rebels and activists dismissed the government’s claims as propaganda, which they claim tries to justify regime infractions of the Russian-Turkish agreement. Karim Obeid, a member of the Aleppo Media Centre, told <em>The National</em> that the Syrian government fabricated the gas attack to justify breaking the demilitarisation deal. Abdel-Salam Abdel-Razak, an official from the Nour el-Din al-Zinki insurgent faction, said rebels did not own chemical weapons or have the capacity to produce them. "The criminal regime, under Russian instructions, is trying to accuse the rebels of using toxic substances in Aleppo. This is purely a lie," he tweeted. The Syrian foreign ministry released a statement on Sunday accusing "foreign states" of providing rebels and militants with chemical weapons. It said that the aim was to blame the Syrian government for chemical weapons attacks carried out by opposition forces. A cease-fire in Aleppo and Idlib has been fraying in recent days. Aleppo has come under rebel attack in recent weeks, with missiles falling inside the city. The government has responded with counter attacks on rebel-held areas in the Aleppo countryside. Earlier Saturday, rescue works and the Britain-based Syrian Observatory for Human Rights said government shells landed in Jarjanaz, a rebel-held town in Idlib province, hitting students as they were leaving their school. The shelling killed eight, including six children, according to the civil defense team in the opposition-held area.