UN Secretary-General Ban Ki-moon on Wednesday called for the end of the cycle of violence that has plagued Gaza for years, as Palestinians were considering extending the cease-fire that went into effect the day before.

Addressing the UN General Assembly at an informal meeting on the humanitarian situation in Gaza, Ban called for swift investigation of the attacks on UN. premises and other suspected breaches of international law.

"UN shelters must be safe zones, not combat zones. Those who violate this sacred trust must be subject to accountability and justice," he said. "Mere suspicion of militant activity does not justify jeopardizing the lives and safety of many thousands of innocent civilians."

"Do we have to continue like this?" Ban said. "Build, destroy and build and destroy? We will build again, but this must be the last time to rebuild. This must stop now."

People on both sides of the conflict, he said, have the right to life "free from fear."

Ban thanked UN staff working in Gaza for their bravery and sacrifice, and said that the UN flag would fly at half-mast Thursday to honor fallen colleagues.

Robert Serry, UN special envoy for the Middle East Peace Process, told the assembly that solutions addressing the root causes of the conflict have been identified, but have yet to be implemented.

"The basic equation is: end the blockade on Gaza, address Israel's legitimate security needs," Serry said.

Pierre Krahenbuhl, commissioner general of the UN Reliefs and Works Agency (UNRWA), warned the assembly that even once a durable cease-fire has been reached, Palestinians will be in dire need of assistance, as many of them will return to destroyed homes with no water or electricity.

He told the UN General Assembly that United Nations flags across the Palestinian territories were flying at half-mast on Wednesday in memory of 11 UN staff killed in the conflict, and said 90 UN buildings had been damaged and that there had been attacks on six UN schools that killed dozens of Palestinian civilians who had sought shelter.

Riyad Mansour, Palestinian ambassador to the UN, where the country has nonmember permanent observer status, said the "barbaric Israeli military campaign" has caused "unbearable inhumane conditions" in Gaza and thanked the UN for providing a "lifeline."

Mansour noted that there was "no symmetry" in the conflict, saying that Israel's "premeditated military aggression" was not justified by its right to self-defense.

Ron Prosor, Israeli ambassador to the UN, said Israel had given "every inch of Gaza" to Palestinians and had no interest in taking it back.

"Gaza could have turned into an amazing place," Prosor said. "We left Gaza never to look back into Gaza, but look at what Hamas has created in Gaza."

Prosor said Israel did everything to avoid the current conflict, noting that it was Hamas that rejected every offer of a cease-fire.

He also said that disarmament of Hamas is the only way to achieve sustained quiet in Israel and Gaza, and that Hamas is committing a double war crime: Targeting Israeli civilians while hiding behind Palestinian civilians.

"Instead of moral clarity, we see moral ambiguity" emerging from certain UN bodies, Prosor said, accusing the UN of caving to anti-Israel tendencies being pushed by some UN members. Comparing Hamas to Islamic State militants in Iraq, Prosor called on the UN to stand with Israel "in its fight against barbarism" before it is too late, before "terror lands on the doorsteps of your own nations."

Meanwhile, the Palestinians are considering extending the 72-hour cease-fire in the Gaza Strip that went into effect on Tuesday, a West Bank-based news agency quoted an official attending peace talks in Egypt as saying.

Hamas official Izzat Rishq told Maan news agency on Wednesday that a decision on a durable cease-fire depended on the outcome of Egyptian-mediated indirect talks with Israel.

Israel sent a delegation to Cairo on Tuesday for indirect talks with the Palestinians through Egyptian and American mediators.

The Palestinians want Israel to end its crippling eight-year blockade on the Gaza Strip, among other demands, before they would agree to any long-term cease-fire.

Israel is conditioning ending the blockade on disarming all militants in the Gaza Strip and dismantling their weapons, mainly the missiles they fire across the border.

Rishq denied media reports that Israel had rejected all Palestinian demands, and said the talks were progressing.