World leaders must put aside disagreements to end the four-year war in Syria that has exacted an "unconscionable" human cost, top UN officials said on Friday.

World leaders must put aside disagreements to end the four-year war in Syria that has exacted an "unconscionable" human cost, top UN officials said on Friday.

"We need world leaders to put aside their differences and use their influence to bring about meaningful change in Syria," the heads of several United Nations agencies said in a joint statement.

"The future of a generation is at stake. The credibility of the international community is at stake," it said.

Syria's conflict has left more than 210,000 people dead and 11.4 million displaced since it began in March 2011.

More than 12.2 million people in the war-torn country need life-saving aid and 3.9 million of those displaced have become refugees in neighboring countries and further afield.

Syria's conflict "continues to exact an unconscionable human cost. A crisis that the international community has failed to stop," said the heads of the UN agencies for humanitarian affairs, health, food aid, refugees, Palestinian refugees and for children.

Their comments echoed a statement from UN chief Ban Ki-moon Thursday warning that the Syrian people "feel increasingly abandoned by the world."

The suffering continues "under the eyes of the international community, still divided and incapable of taking collective action to stop the killing and destruction," he said.