Facing a worsening humanitarian crisis in Syria, the United Nations Security Council unanimously approved a resolution Tuesday demanding that all combatants but especially the Syrian government allow the urgent delivery of desperately needed food and medicine to more than 13.5 million people.

The council expressed "outrage" at the escalating violence in Syria, grave distress at "the devastating humanitarian situation" and growing concern at the increasing impediments to the delivery of aid, especially across front lines in the conflict. The resolution extends the authorization for cross-border aid deliveries until Jan. 10, 2017. It previously authorized deliveries through four crossings two in Turkey, one in Iraq that has not been used, and one in Jordan.

Of the more than 13.5 million people in need of food and medical assistance inside the country, the council said 6.5 million have fled their homes, 4.5 million including Palestinian refugees are living in hard-to-reach areas, and 393,700 are trapped in besieged areas.

It expressed "grave alarm" especially for those in besieged areas where the U.N. was only able to reach 3.5 percent with health assistance and just 0.7 percent with food monthly in 2015. The Security Council also accused DAESH which now controls about a third of Syria, the Al-Nusra Front and other al-Qaida associates of hindering aid deliveries including to nearly half the people in hard-to-reach areas and over half the people in besieged areas "through deliberate interference and obstruction."

U.S. Ambassador Samantha Power said after Tuesday's vote that the resolution "underscores the urgent need for assistance across conflict lines." She accused the Syrian government of delaying approval for deliveries across conflict lines, where more than half the requests made in 2015 are still pending.

The U.N. is appealing for nearly $3.2 billion to assist the 13.5 million needy Syrians inside the country in 2016 and Kang called on donors to contribute generously.