U.N. chief Antonio Guterres pleaded Saturday for a "humanitarian cease-fire" in the war between Israel and Hamas militants that has devastated much of Gaza, demanding "action to end this godawful nightmare."

Addressing a Cairo summit as the conflict raged into its third week, Guterres said the Palestinian enclave of 2.4 million people was living through "a humanitarian catastrophe" with thousands dead and more than a million displaced.

"We meet in the heart of a region that is reeling in pain and one step from the precipice," he told the meeting that included the leaders of Egypt, Iraq, Jordan and the United Arab Emirates as well as of Italy and Spain and Palestinian leader Mahmud Abbas.