U.N. Secretary-General Ban Ki-moon has warned of an “epic humanitarian catastrophe” in a Palestinian refugee camp invaded by the self-proclaimed Islamic State in Syria. Speaking Thursday, Ban said Yarmouk resembles a death camp.

Ban Ki-moon: “The Yarmouk refugee camp is the deepest circle of hell. After more than two years of a merciless siege, 18,000 Palestine refugees and Syrians are now being held hostage by Daesh and other extremist militants. A refugee camp is beginning to resemble a death camp. The residents of Yarmouk, including 3,500 children, are being turned into human shields. They face a double-edged sword — armed elements inside the camp and government forces outside.”

Palestinian officials have rejected the possibility of joining with the Syrian government to oust the ISIL militants. The statement from the Palestine Liberation Organization contradicts an earlier statement from the PLO’s envoy to Syria suggesting the Palestinians would join in military action.