(Reuters) - Saudi Arabia and other Muslim countries called on Saturday for an immediate end to military operations in Gaza, rejecting Israel's justification of its actions against Palestinians as self-defence.

The extraordinary joint Islamic-Arab summit in Riyadh urged the International Criminal Court to investigate "war crimes and crimes against humanity that Israel is committing" in the Palestinian territories, according to a final communique.

Saudi Arabia has sought to press the United States and Israel for an end to hostilities in Gaza, and Crown Prince Mohammed bin Salman, the kingdom's de facto ruler, gathered Arab and Muslim leaders to reinforce that message.

Dozens of leaders including Iranian President Ebrahim Raisi, Turkish President Tayyip Erdogan, Qatar's Emir Sheikh Tamim bin Hamad Al Thani and Syrian President Bashar al-Assad, who was welcomed back into the Arab League this year, attended.

Prince Mohammed affirmed the kingdom's "condemnation and categorical rejection of this barbaric war against our brothers in Palestine".

"We are facing a humanitarian catastrophe that proves the failure of the Security Council and the international community to put an end to the flagrant Israeli violations of international laws," he said in an address to the summit.

Palestinian President Mahmoud Abbas said Palestinians were facing a "genocidal war" and urged the United States to end Israeli "aggression".

Raisi hailed the Palestinian Islamist militant group Hamas for fighting against Israel and urged Islamic countries to impose oil and goods sanctions on Israel.

"There is no other way but to resist Israel. We kiss the hands of Hamas for its resistance against Israel," Raisi said in his address.

The Middle East has been on edge since Hamas fighters rampaged into Israel on Oct. 7, killing 1,200 people.

Since then, Israel has escalated its assault on Gaza, where 11,078 people had been killed as of Friday, 40% of them children, according to Palestinian officials.