The Organisation of the Islamic Conference (OIC), the world's largest Islamic body, accused Israel of war crimes on Wednesday after Palestinians said 18 civilians were killed in an attack on Gaza.
"This affirms that Israel scorns international law and insists on continuing to commit war crimes and violate the Fourth Geneva Convention, and an international effort is required to stop this killing," the Saudi-based OIC said.
The statement asked the United Nations Security Council to take urgent measures "to stop the Israeli attack and to guarantee the protection of the Palestinian people from Israel's brutality and state terrorism".
Early on Wednesday Israeli tank shells killed 18 civilians in the Gaza town of Beit Hanoun, in one of Israel's deadliest strikes in the territory in months, Palestinian officials and residents said. Palestinian authorities said the dead included seven children and four women, and 54 people had been wounded.
Israel withdrew from the northern town on Tuesday following a week-long assault, designed to stop militants firing rockets at the Jewish state, that killed 52 militants and civilians.
Palestinians have been fighting since 2000 to declare an independent state in territories seized by Israel in 1967 where Israel has allowed them a form of self-rule.