Two convoys of aid which crossed the Turkish border into Syria were waiting in no-man's land for permission to travel onwards towards Aleppo on Wednesday, as disagreements between warring sides delayed aid deliveries on the third day of a ceasefire.
The convoys, each of around 20 trucks carrying mostly food and flour, crossed into Syria from the Turkish border town of Cilvegozu, about 40 km (25 miles) west of Aleppo, on Tuesday but made it little further than the Turkish customs post.
The international community's first goal since the truce brokered by the United States and Russia came into effect on Monday is to get aid to Aleppo. The city, Syria's biggest before the civil war that broke out in 2011, is now divided, and its rebel-held area is besieged by government forces.
"Things are taking longer than we'd hoped," David Swanson, spokesman for the U.N. Office for the Coordination of Humanitarian Affairs (OCHA) told Reuters, adding that 20 U.N. trucks were waiting at the border "ready to go".
The Syrian government has said it will reject any aid deliveries to the city not coordinated through itself and the United Nations, particularly from Turkey, which has backed the rebels fighting President Bashar al-Assad.
The ceasefire has drastically reduced fighting across the country between Syrian government forces and insurgents. But a similar truce in February gradually broke down and violence escalated sharply, particularly around Aleppo.
Swanson said disagreements between the warring sides were blocking aid getting into opposition-held eastern Aleppo.
"Some groups are looking to gain political mileage out of this, and this is something we need to put aside," he said.
"In addition to eastern Aleppo, U.N. humanitarian operations inside Syria are also ready to deliver life-saving assistance to other besieged and hard-to-reach locations ... but only once access is possible."
The U.N. estimates that well over half a million people are living under siege in Syria, whose five-year conflict has killed hundreds of thousands and displaced more than 11 million.
The U.N. special envoy for Syria, Staffan de Mistura, said on Tuesday that the U.N. was still waiting for Damascus to issue letters authorising aid deliveries. The Turkish official said no further trucks were expected to cross the border on Wednesday until the situation became clearer.