BEIRUT (AP) — The head of the U.N. agency that supports Palestinian refugees said Friday that progress has been made in providing food to some 18,000 civilians trapped in the Yarmouk refugee camp in the Syrian capital, but an agreement must be struck to also allow in desperately needed medical aid.

Yarmouk, the largest of nine Palestinian camps in Syria, has been under a tight government blockade since mid-2013. More than 100 people have died there from starvation and illnesses exacerbated by hunger or lack of medical aid, according to U.N. figures.