Egypt on Friday condemned Israel's "irresponsible" escalation in Gaza, urging the international community to swiftly intervene as Israeli airstrikes continued for a fourth day. 

Egypt's foreign ministry said Cairo rejected Israel's excess use of military force and the collective punishment policy it is adopting against the Palestinians.

At least 90 Palestinians, including many women and children, have been killed, and more than 600 injured, since the beginning of the Israeli campaign in the coastal enclave on Tuesday, according to Palestine's health ministry figures.

"Egypt rejects Israel's irresponsible escalation in the occupied Palestinian lands amid its excess and unjustifiable use of military force and the subsequent bloodshed of innocent civilians," read a statement by the Egyptian foreign ministry on Friday.

"This constitutes a perpetuation of the repression and collective punishment policies."

Cairo has called on Israel to exercise self-restraint, respect humanitarianism and abide, as an occupation force, by legal and ethical commitments to protect the lives of civilians, the statement added

Israeli leaders have approved the call-up of 40,000 reservists for a possible ground invasion, Israeli daily Haartez reported, while the Islamist movement Hamas, the dominant force in Gaza, has continued its rocket fire. No Israeli casualties have been reported as a result of the rockets.

Egypt urged swift intervention by the world powers to put a stop to the bloodshed, slamming on Friday the "obstinacy and stubbornness" its days-long efforts and contacts with involved parties, to urge an end to violence and the restoration of the 2012 ceasefire, have been met with.

It vowed the Palestinian issue will continue to top its foreign agenda, emphasising its "full backing" to the Palestinian people.

The recent violence is the deadliest since a 2012 ceasefire agreement, brokered by Egypt and the US, ended eight days of Israeli airstrikes on Hamas targets.

As the violence in Gaza intensifies, Egypt on Thursday opened the Rafah border crossing to receive wounded Palestinians seeking treatment, with officials saying hospitals in North Sinai, which borders Gaza and Israel, placed on standby to receive the wounded.

US secretary of State John Kerry spoke to his Egyptian counterpart and reached out to Qatar in a bid to get both states to use their influence to quell the fighting, State Department spokeswoman Jen Psaki said.

The Israeli offensive followed a build-up in violence after three Israeli settlers were killed in the occupied West Bank last month and a Palestinian youth was killed in a suspected revenge attack in Jerusalem.

Israel says it has struck more than 860 targets in Gaza. Palestinian rocket fire escalated after Israeli forces arrested hundreds of Hamas activists in the West Bank while searching for the youths, whom Israel said were abducted and killed by Hamas.