U.N. Secretary General Ban Ki-moon lamented the vast destruction in Gaza as he visited the area on Tuesday for the first time since the war, calling the situation "beyond description" and urging a speedy reconstruction effort, Reuters reported.
He also announced that Israel was permitting a first truckload of construction materials to enter the enclave, which has been blockaded by Israel and Egypt since before the conflict.
In a short visit under tight security, Ban toured areas that were heavily bombarded by Israel during the 50-day war, in which more than 2,100 Palestinians, most of them civilians, were killed. Sixty-seven Israeli soldiers and six civilians in Israel also died at the hands of Hamas rockets and other attacks.
"I am here with a heavy heart," Ban told a news conference. "The destruction which I have seen coming here is beyond description," he added, calling it much worse than what he had witnessed after the last war in 2008-9.
More than 1.8 million Palestinians live in Gaza, an area about 40 km long (25 miles) and 10 km wide at its widest point.
An estimated 20,000 homes were heavily damaged or destroyed in the fighting, while the territory's power station and other major pieces of infrastructure were hit. Contractors say it could take years to rebuild.
At a conference in Cairo on Sunday, international donors pledged a larger-than-expected $5.4 billion for Gaza's reconstruction, although a large portion of that money will go to support the Palestinian budget, not directly to rebuild homes and Gaza's infrastructure.
During his visit, Ban met with members of the Palestinian unity government that was formed following an agreement in April between the Palestinian Authority, led by Fatah, and Hamas, the Islamist militant group that dominates in Gaza.
The unity government, which contains no Hamas members and is largely technocratic, met for the first time last week. It allowed for the Palestinian Authority to take over responsibility for administering Gaza, a step Israel wanted to see before allowing a freer flow of goods into the territory.
"We stand by you, the international community supports your government's efforts to assume the security and governance responsibility in Gaza," Ban said of the unity cabinet.
On Monday, Ban criticised Israel for its continued building of settlements on land the Palestinians seek for an independent state and urged both sides to return to meaningful negotiations as soon as possible.