Geneva - Senior United Nations officials have voiced concern over the world body's failure to meet targets in the delivery of humanitarian aid to areas of war-ravaged Syria, though they have hoped for a breakthrough in negotiations to restart peace talks.Only 40% of the aid planned for areas in Syria was delivered in June and July, the head of a UN-backed humanitarian taskforce for Syria said on Thursday.There is "fighting in too many places and that affects the besieged towns more than anything else," humanitarian adviser Jan Egeland said, adding that the UN failed to reach its goal of helping 1.2 million Syrians during the two-month period.The UN has in recent days pinned hopes on efforts by Moscow and Washington to restore a ceasefire in Syria as fighting intensifies.Ramzy Ezzeldin Ramzy, the UN deputy envoy for Syria, said US-Russian negotiations were ongoing and that the UN remained "committed" to relaunching peace talks in late August."There is still time, we cannot give up hope. Bear with us and I think in next few days there might be some movement" towards holding "credible talks," Ramzy told reporters in Geneva.Barrel bombs"We need to do something about Aleppo and very quickly. There is still a chance for that in the next days."Once Syria's largest city, Aleppo has been roughly divided between government control in the west and rebel control in the east since mid-2012.After cutting off the last remaining rebel supply route to the eastern half of the city, government forces have reportedly begun retaking rebel-controlled parts. "According to opposition activists, most of the victims were killed by air strikes and barrel bombs by Syrian government forces," a report from Gaziantep on the Turkish border with Syria said, adding that both sides in the conflict are blaming one another for the civilian casualties."The activists also said a refugee camp and an aid convoy were hit in those air strikes," the report said.