BEIRUT: A U.N. aid chief said Monday he was "pained and disappointed" that aid which has been sitting on the Turkey-Syria border for a week has not yet reached besieged eastern Aleppo.

"I am pained and disappointed that a United Nations convoy has yet to cross into Syria from Turkey, and safely reach eastern Aleppo, where up to 275,000 people remain trapped without food, water, proper shelter or medical care," the U.N. Under Secretary General for Humanitarian Affairs Stephen O'Brien said in a statement.