United Nations Secretary General Ban Ki-moon demanded an end to growing civil conflict in South Sudan and called on all parties Sunday to negotiate a political solution to the crisis.

“I demand that all political, military and militia leaders stop hostilities and end the violence against civilians,” he said.

“They’re responsible to the people of South Sudan to end the crisis and find a political means of addressing their differences.” Mr. Ban urged South Sudan President Salva Kiir and opposition leaders including former vice president Riek Machar to negotiate “to find a political way out of this crisis.” “I call on them to do everything in their power to ensure that their followers share the message loud and clear that continued violence, ethnic and otherwise, is completely unacceptable and pose a dangerous threat to the future of your country,” he said.

Mr. Ban said the UN’s priority is to protect more than 40,000 civilians who have taken refuge in various shelters amid the deteriorating security situation.

“For that we are now actively trying to transfer our assets from other peacekeeping missions,” he said. “We are also seeking the support of other key countries who can provide the necessary asset.” Mr. Ban said the UN faces “a shortage in capacity” after the UN compound in the area was overrun by 2,000 gunmen who killed two peacekeepers.