UN chief Antonio Guterres pleaded on Saturday for a "humanitarian ceasefire" 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 president Mahmud Abbas.
The bloodshed began on October 7 when Hamas militants killed at least 1,400 people, mostly civilians who were shot, mutilated or burnt to death on the first day of the raid, and took more than 200 hostages, according to Israeli officials.
Israel says around 1,500 Hamas fighters were killed in clashes before its army regained control of the area under attack.
Israel has hit back with a relentless bombing campaign, killing more than 4,300 Palestinians, mainly civilians, according to Gaza's Hamas-run health ministry, and cut off supplies of water, electricity, fuel and food.
Guterres said "the grievances of the Palestinian people are legitimate and long" after "56 years of occupation with no end in sight" but stressed that "nothing can justify the reprehensible assault by Hamas that terrorised Israeli civilians".
He then stressed that "those abhorrent attacks can never justify the collective punishment of the Palestinian people".
Jordan's King Abdullah II called for "an immediate end to the war on Gaza" and condemned what he labelled "global silence" on Palestinian death and suffering.
"The message the Arab world is hearing is loud and clear: Palestinian lives matter less than Israeli ones. Our lives matter less than other lives," he charged.
"The application of international law is optional. And human rights have boundaries -- they stop at borders, they stop at races, and they stop at religions."
'We will not leave'
The summit came on the day a first convoy of aid trucks rumbled into southern Gaza, which Guterres said needed to be rapidly scaled up, with "much more" help sent through.
The UN has said that about 100 trucks per day are needed to meet worsening needs in Gaza.
The Palestinians need "a continuous delivery of aid to Gaza at the scale that is needed", the UN chief told the Cairo "Summit for Peace".
Egypt's President Abdel Fattah al-Sisi argued that the "only solution" to the Israeli-Palestinian conflict is "justice" and said that "Palestinians must realise their legitimate rights to self-determination" and have "an independent state on their land".
Palestinian president Mahmud Abbas stressed his demand for a two-state solution and an "end to Israel's occupation" and rejected what he has warned could be a "second Nakba" -- a reference to the more than 760,000 Palestinians who fled or were driven from their lands during the creation of the state of Israel.
"We will not leave," he repeated three times at the end of his speech.
Cairo and Amman have repeatedly rejected calls for large numbers of refugees to enter Egypt from Gaza, warning that a "forced displacement" of Palestinians would lead to the "eradication the Palestinian cause".
Egypt and Jordan were the first Arab states to normalise relations with Israel, in 1979 and 1994 respectively, and have since been key mediators between Israeli and Palestinian officials.
Turkey's foreign minister Hakan Fidan urged for the current conflict to become, "rather than a regional conflagration, a breeding ground for a just and lasting peace".
He also condemned "unconditional military aid to Israel which only serves to maintain the occupation", while Saudi Arabia's Foreign Minister Prince Faisal bin Farhan condemned the failure of the UN Security Council to pass a resolution calling for a ceasefire after a US veto.