U.S. Secretary of State John Kerry left for Cairo Saturday to back calls to aid the Gaza Strip, amid fears donors may fail to raise $4 billion needed to rebuild the Palestinian territory.

Egypt will be the first step on a fresh whirlwind tour for the 70-year-old top U.S. diplomat, who will also hold meetings in Paris and Vienna on the crisis in Ukraine and efforts to reach an Iran nuclear deal with a deadline just a few weeks away.

Envoys from dozens of countries will gather Sunday for a conference that aims to raise billions of dollars to rebuild conflict-battered Gaza, despite fears of renewed violence and "donor fatigue".

The United Nations' Palestinian refugee agency has described the financial needs as "unprecedented" ahead of the Cairo meeting, which follows the Gaza Strip's third war in six years.

The U.N.'s Palestinian refugee agency is to make its largest ever financial plea to donors, it said on Thursday, asking for $1.6 billion (1.26 billion euros) to rehabilitate war-battered Gaza.

The conflict between Israel and Hamas-led Gaza militants, which ended on August 26, killed nearly 2,200 Palestinians, most of them civilians, and 73 people on the Israeli side, mostly soldiers.

The Palestinian unity government held its first ever meeting in the war-ravaged Gaza Strip on Thursday as its rival factions presented a common front ahead of a major donors' conference.

The gathering came more than four months after the government was sworn in following a landmark reconciliation deal between Fatah and Hamas.

Surrounded by the rubble of a deadly war with Israel, Gazans marked a sombre Eid al-Adha festival Saturday with prayers and visits to the graves of relatives.

Thabet al-Hamami pitched a tent by the ruins of his home -- one of 60,000 totally or partially destroyed by Israeli strikes during the recent conflict -- and offered sweets to relatives and friends.

The Palestinian government on Thursday in a reconstruction plan for Gaza ahead of an October 12 donor conference called for $4 billion to rebuild the war-battered territory.

Gaza's infrastructure was devastated during a 50-day Israeli military operation which killed nearly 2,200 Palestinians, while attacks by Gaza militants killed 73 on the Israeli side.

Israeli Prime Minister Benjamin Netanyahu has complained U.N. chief Ban Ki-moon that a probe by the world body into the Gaza war is one-sided, his foreign ministry said Wednesday.

At a meeting with Ban on Tuesday in New York, Netanyahu charged that the U.N. Human Rights Council "is not focusing its inquiry on Hamas, which used U.N. facilities in order to fire at Israel," a ministry statement said.

Most Palestinians would favor resuming rocket fire at Israel if it does not lift its Gaza blockade, although support for armed confrontation is dropping off, according to a poll published Monday.

"An overwhelming majority of 80% supports the launching of rockets from the Gaza Strip at Israel if the siege and blockade are not ended," said the survey of 1,200 Palestinians in Gaza and the West Bank conducted by the Palestinian Center for Policy and Survey Research (PSR).

Israeli troops shot and wounded a 14-year-old boy in the northern Gaza Strip on Monday in the second such incident in 24 hours, medics said.

The boy suffered injuries to his foot after coming under fire in his village close to the border, emergency services spokesman Ashraf al-Qudra said in a statement.

Palestinian leader Mahmud Abbas demanded on Friday an end to Israeli occupation, telling the United Nations that the time for Palestinian independence had come.

Abbas also vowed to seek war crimes prosecutions against Israel over what he called the 50-day "war of genocide" in Gaza that killed 2,140 Palestinians, mostly civilians, and left the enclave in ruins.