The people of Syria are losing hope in the fifth year of a civil war that has brought levels of death and destruction, the United Nations chief said Thursday.

The war has killed more than 220,000 people and left a third of the population homeless. Of the country's roughly 23 million people, some 12.2 million are in need of humanitarian aid, including 5 million children, Secretary-General Ban Ki-moon said in his monthly report.

"The level of carnage and devastation throughout the Syrian Arab Republic should shock the collective conscience of the world," said Ban's report, which covers the month of April and was largely prepared by outgoing U.N. humanitarian chief Valerie Amos.

"The Syrian people are losing hope," he said. "They cannot afford to wait. A political solution must be found.

"The conflict will end with a political settlement, not with a military solution," Ban added.

"The sooner that that is recognized by all those engaged in the conflict, the better it will be for the Syrian people and the more lives will be saved."