US-led strikes targeting the Islamic State (ISIS) jihadist group killed at least 52 civilians in northern Syria, a monitor said Saturday, but the Pentagon said it could not confirm the report. The Syrian Observatory for Human Rights monitor also reported 10 civilian deaths in a rocket strike Saturday in the northern city of Aleppo and said 40 others suffered respiratory problems in a pre-dawn chemical attack further north in Idlib province. Observatory director Rami Abdel Rahman told AFP that US-led coalition strikes early Friday on the village of Birmahle in Aleppo province killed 52 civilians. He said "seven children" were among the dead but that the toll could rise as 13 people were still trapped under rubble. Kurdish militiamen and Syrian rebel fighters were clashing with ISIS jihadists in a town roughly two kilometers (1 mile) away from Birmahle at the time of the strikes. "Not a single ISIS fighter" was killed in the strikes on Birmahle, said Abdel Rahman, adding that the village is inhabited by civilians only and that ISIS has no positions there. US Central Command spokesman Colonel Patrick Ryder told AFP there was "no information to corroborate allegations that coalition air strikes resulted in civilian casualties." "Regardless, we take all allegations seriously and will look into them further," he added. The incident brings to mind reports last November showing that 96.5% of the casualties from US drone strikes in the Middle East were civilians, a figure which shows how remarkable the IDF's 1:1 ratio of civilian to combatant casualties in Gaza was last summer despite Hamas's embedding of its terrorist infrastructure in civilian centers. Rocket fire hits Aleppo News of the deaths come as Canadian Prime Minister Stephen Harper visited Iraq, days after lawmakers in Ottawa voted to expand their country's contribution to the US-led coalition against ISIS. Air strikes by the international coalition have supported Kurdish militias fighting ISIS in Aleppo province, most notably in the flashpoint border town of Kobane, which is near Birmahle. Backed by the strikes, Kurdish fighters drove jihadists out of Kobane in January. A statement released on Friday by the coalition's joint task force said it had conducted six air strikes near Kobane on ISIS tactical units. Prior to Friday's strikes, the coalition's raids had killed 66 civilians since it began attacking ISIS positions in Syria in September 2014. According to the Britain-based Observatory, the air campaign has killed more than 2,000 people in total, including at least 1,922 ISIS fighters. In Aleppo, at least 10 civilians, including three children, were killed in rebel rocket attacks Saturday on regime-controlled parts of the divided city. Dozens were seriously wounded, said Abdel Rahman who expected the death toll to rise. Syrian state television blamed "terrorists" for the rocket attacks, which it said killed 12 people and wounded 45. "Chlorine" attack The attacks came despite the death Friday night of a rebel commander known for launching rockets and mortar rounds on regime-held parts of Aleppo. Abdel Rahman said that Khaled Hayyani was killed by pro-regime snipers, and described him as a "dangerous man who was responsible for over 550 deaths, including 130 children, in 2014." Also on Saturday, at least 40 civilians, including children, suffered respiratory problems in "chlorine gas attacks" on two rebel-held villages in northwestern Idlib province, the Observatory said. The monitor said regime forces dropped barrel bombs filled with chlorine - a toxic agent that can be considered a chemical weapon - on Saraqeb and Nairab causing the deaths. A video posted by activists online showed paramedics splashing a toddler with water, while other children - some coughing - breathed through gas masks. The video could not be independently verified by AFP . The Observatory, which relies on a network of sources inside Syria, said a baby had died in Nairab. Activists have accused the Syrian regime of using chlorine on civilian areas in the past. In January, the Organization for the Prohibition of Chemical Weapons (OPCW) said chlorine gas had been used in attacks on three Syrian villages in 2014.