By Firas Makdesi
DAMASCUS, April 12 (Reuters) - The head of the U.N. agency responsible for Palestinian refugees called from Damascus on Sunday for safe passage for people wishing to leave the Yarmouk camp on the city fringes that Islamic State insurgents are trying to take over.
UNRWA Commissioner General Pierre Krahenbuhl and another senior U.N. official are in the Syrian capital to find ways to ease the plight of some 18,000 people estimated to be trapped in Yarmouk, which has been under government siege since 2013.
A Syrian military source said the army was giving a chance for solutions aimed at resolving the situation in Yarmouk, which U.N. Secretary General Ban Ki-moon has said is "beginning to resemble a death camp."
Islamic State's arrival in Yarmouk has given the jihadist group a significant foothold a few kilometers (miles) from President Bashar al-Assad's seat of power.
Islamic State, which has already seized wide areas of eastern and northern Syria, has in recent weeks mounted several big attacks on regions closer to the main population centers of western Syria, both in government- and rebel-held areas.
Ban said last Thursday that residents of Yarmouk were being "held hostage" by Islamic State militants and other extremists.
He also said they "face a double-edged sword - armed elements inside the camp, and government forces outside."
Islamic State moved into Yarmouk last week. Aided by fighters from the al Qaeda-linked Nusra Front, it has seized large parts of the camp from other insurgents based there.
Krahenbuhl visited a Damascus school where he met several dozen evacuees from Yarmouk. "We are very concerned of course about the survival needs of the people inside Yarmouk," he said.
"We called for a very clear respect for the civilians who are inside Yarmouk, we called for the possibility for civilians to temporarily leave in a safe way Yarmouk, to be able to be assisted outside. We will continue to call for this.
"We are thinking very strongly of how we can provide some form of assistance to the people who are inside," he added.
The Syrian Observatory for Human Rights, a Britain-based group that monitors the four-year-old civil war via sources on the ground, has reported army air strikes on the camp since Islamic State moved in.
The military source told Reuters that was "absolutely not true," adding: "We are waiting, leaving the space for solutions that safeguard the situation of the civilians and their situation."
Ramzi Ezzedine Ramzi, deputy to the U.N. envoy to Syria, told Reuters on Saturday he left a meeting with Syrian Deputy Foreign Minister Faisal Mekdad on Saturday "quite satisfied and confident that there will be very good cooperation." (Writing/additional reporting by Tom Perry in Beirut; Editing by Mark Heinrich)