MADRID — Medical charity Medecins Sans Frontieres (MSF) said on Tuesday it had treated a Syrian family with symptoms of exposure to chemical agents from an area where Islamic State fighters have been battling other rebels. Two adults, a three-year-old girl and a five-day-old baby girl were treated at an MSF-run hospital in Aleppo province, northern Syria, last Friday, the charity said in a statement. They arrived at MSF's hospital an hour after the attack, suffering from breathing difficulties, inflamed skin, red eyes and conjunctivitis. Within three hours they developed blisters and their breathing difficulties worsened, the statement said. MSF staff treated them and gave them oxygen before transferring them to another hospital for specialized treatment. The family came from the town of Marea, north of Aleppo, where Daesh (the so-called IS) recently launched a new offensive against other Syrian rebels. The town, 20 km (12 miles) south of the border with Turkey, had been under intense bombardment by mortars and artillery for a week, MSF said. “If it was a chemical attack, it is impossible for us to ascertain who was responsible,” Pablo Marco, MSF's program manager in Syria, told Reuters. The family said a mortar shell hit their home last Friday evening, MSF said. After the explosion, a yellow gas filled their living room. “MSF has no laboratory evidence to confirm the cause of these symptoms,” Marco said in the statement. “However, the patients' clinical symptoms, the way these symptoms changed over time, and the patients' testimony about the circumstances of the poisoning all point to exposure to a chemical agent.” Daesh used poison gas in attacks against Kurdish-controlled areas of northeastern Syria in late June, a Syrian Kurdish militia and a group monitoring the Syrian conflict said in July. A US general said last Friday that fragments from mortars fired by Daesh militants at Kurdish fighters in northern Iraq earlier this month tested positive in a US military field analysis for sulphur mustard, a chemical weapons agent. Marine Corps Brig. Gen. Kevin Killea, chief of staff for operations against the group, said the test was not conclusive proof of chemical weapons use, and the fragments would be further tested to confirm the finding. Syrian President Bashar Al-Assad agreed with the United States and Russia to dispose of the government's chemical weapons — an arsenal which Damascus had never formally acknowledged — after hundreds of people were killed in a sarin gas attack on the outskirts of the capital in August 2013. — Reuters