“We as the UN do not know who sent in the mortars in western Aleppo that may have included chemical agents,” said Jan Egeland, co-chair of the International Syria Support Group’s Humanitarian Access Task Force and Senior Advisor of the UN Special Envoy for Syria. “Therefore, the OPCW, the Organization for the Prohibition of Chemical Weapons, will investigate; the World Health Organization (WHO) has rushed medical supplies to the hospitals treating these people. If it is use of a chemical weapon, it is a war crime.”Mr. Egeland’s comments coincide with an escalation of fighting in Idlib in northern Syria, which is home to opposition militants and around three million civilians.All hell was let loose on them and no one was willing and able to shield and protect them – Jan Egeland reflects on the plight of Syrian civiliansThe escalation was a “giant powder keg” in a heavily populated area, he warned, adding that airstrikes had resumed after two months of relative calm.“What is true is that a number of groups have sent a number of grenades out of the zone,” Mr. Egeland said, “and that Government and other forces have sent – as I see it, equal numbers of grenades – into the zone.”A fragile ceasefire between Government forces and opposition fighters has held in Idlib for 10 weeks, guaranteed by Russia, Turkey and Iran, who re-committed to the deal at talks in Astana, Kazakhstan, on Thursday.Mr. Egeland, who welcomed the original deal, warned at the time that the alternative – clashes between opposition and Government forces – would cause massive bloodshed and destruction similar to that inflicted on other major cities, including Homs, Aleppo, and Raqqa.In his last press encounter as co-chair of the humanitarian task force before stepping down, Mr. Egeland offered insight into the difficulties of achieving the mechanism’s two main aims since it was established in early 2016: securing aid access and protecting civilians.Among its challenges were the fact that towns and villages had been besieged, hundreds of thousands of people had died and 12 million had been driven from their homes during the more than seven-year war, he noted.Turning to the 23 countries that attended task force meetings in Geneva, Mr. Egeland insisted that “too few acted courageously” to hold back the warring parties’ worst excesses against civilians.“All hell was let loose on them and no one was willing and able to shield and protect them,” he said, adding nonetheless that “what happened here in Geneva helped cause some of the few really achievements, also in the protection of civilians”.The task force’s successes included securing aid deliveries to the majority of people in besieged areas in 2016, Mr. Egeland said, compared with only two per cent a year earlier, and organizing the first high-altitude air-drops of aid to besieged people in Deir Ez-Zor in eastern Syria.’No tangible progress’ at latest talks to end Syria warIn a joint statement released on Thursday from Astana – where regular meetings have been held since January 2017 – Iran, Russia and Turkey reiterated their support for the UN-backed launch of a Constitutional Committee for Syria in Geneva “that would enjoy support of the Syrian parties…at the soonest possible time”.Staffan de Mistura, UN Special Envoy for Syria, who has been leading efforts to form a Constitutional Committee, noted on Thursday that the Astana meeting had achieved “no tangible progress” in resolving a 10-month stalemate on its composition, as had been outlined in Sochi in January this year.