GENEVA, 18th August 2016 (WAM) — No aid convoys have reached civilians trapped in besieged areas of Syria this month and a humanitarian task force has been suspended as a warning to big powers to double down on securing a ceasefire, the U.N. peace envoy on Syria said on Thursday.

Staffan de Mistura said a 48-hour pause in fighting in the northern city of Aleppo was the main goal for a meeting later in the day of major and regional powers tasked with resurrecting a collapsed cessation of hostilities accord.

“I again insist on behalf of the Secretary General of the U.N. and of all the Syrian people (on having) a 48-hour pause in Aleppo to start with,” he was quoted by Reuters as saying in Geneva.

“That would require some heavy lifting from not only the two co-chairs (Russia and the United States) but also those who have an influence on those who are fighting on the ground.”

De Mistura spoke after suspending the weekly meeting of the humanitarian task force after eight minutes “as a sign of deep unhappiness” with the failure to restore calm to enable aid deliveries to stricken civilians in besieged districts.