Egypt, which alongside Qatar and the United States, helped mediate a truce in the Israel-Hamas war that took effect in January, condemned the strikes, branding them a "flagrant violation" of the truce.

In a call between Egyptian President Abdel Fattah al-Sisi and Kuwaiti Emir Sheikh Meshal al-Ahmad al-Sabah, the pair "condemned and denounced Israel's resumption of hostilities".

The statement from Sisi's office said the strikes were part of "deliberate efforts to make the Gaza Strip uninhabitable and force the Palestinians into displacement".

US President Donald Trump has floated a proposal to move Gaza's population out of the war-battered territory, suggesting that Egypt or Jordan could take them in.

Both countries, along with other Arab allies, governments around the world and the Palestinians themselves, have flatly rejected the notion and endorsed a plan to rebuild Gaza without Palestinians relocating.

For Palestinians, any forced displacement evokes memories of the "Nakba", or catastrophe -- the mass displacement in the war that led to Israel's creation in 1948.

In another statement, Egypt's foreign ministry called the strikes a "dangerous escalation which threatens to bring serious consequences for the stability of the region".

Egypt called on the international community to "act immediately to halt the Israeli aggression against the Gaza Strip in order to prevent the region entering a new spiral of violence and counterviolence", the statement said.

Qatar's foreign ministry also condemned the strikes, warning that Israel's "escalating policies will ultimately ignite the region and undermine its security and stability".

Jordan, which like Egypt neighbours Israel, also condemned the strikes, which the health ministry in Hamas-run Gaza said killed more than 400 people.

"We have been following since last night Israel's aggressive and barbaric bombing of the Gaza Strip," government spokesman Mohammed Momani said, underlining "the need to stop this aggression".

Arab League chief Ahmed Aboul Gheit called the strikes "an inhuman act and a challenge to the international will that supported the ceasefire".

"Leaders of the Israeli occupation are waging an internal battle at the expense of the blood of children and women in Gaza, risking the lives of Israeli hostages in the strip," the regional bloc's secretary-general said in a statement.

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