BEIRUT - A United Nations agency delivered food to a rebel-held Damascus district on Thursday, alleviating the plight of thousands of people trapped for months by a Syrian army siege.The UN Relief and Works Agency (UNRWA), which cares for Palestinian refugees, said it had begun distributing 900 food parcels in Yarmouk camp, its biggest delivery there yet.UNRWA spokesman Chris Gunness said the aid was the first to reach Yarmouk since Jan. 21 when 138 food parcels were sent in. Each parcel can feed a family of five for 10 days, meaning the needs of the population still far outstrip aid deliveries."We hope to continue and increase substantially the amount of aid being delivered," said Gunness. "With each passing hour their need increases."Syria's state news agency SANA confirmed the aid delivery, saying Yarmouk's residents were "held hostage by armed terrorist groups" - its usual description of rebel forces.