Dozens of people at the camp are reported to have died from malnutrition and inadequate medical care, Middle East Online reported.
"A first batch of food aid entered successfully this morning and distribution to residents has begun," Palestine Liberation Organization official Anwar Abdul Hadi told the website.
Chris Gunness, a spokesman for the United Nations Relief and Works Agency for Palestine Refugees in the Near East or UNRWA, said the agency contributed 200 food packages, although he said there was no confirmation they had reached the camp. He said the agency received guarantees its aid would be distributed only to refugees, not to fighters.
The camp in the outskirts of Damascus has been under the control of Syrian rebels for months. The Syrian Observatory for Human Rights says 54 people have died from starvation and lack of medical care during that time.