"The United Nations Development Programme's initial estimates for the reconstruction of... the Gaza Strip surpass $30 billion and could reach up to $40 billion," said UN assistant secretary-general Abdallah al-Dardari.

"The scale of the destruction is huge and unprecedented... This is a mission that the global community has not dealt with since World War II," Dardari told a press conference in the Jordanian capital Amman.

He added that if Gaza's reconstruction were to be carried out through the normal process, "it could take decades, and the Palestinian people do not have the luxury of waiting for decades".

"It is therefore important that we act quickly to re-house people in decent housing and restore their lives to normal -- economically, socially, in terms of health and education".

"This is our top priority, and it must be achieved within the first three years following the cessation of hostilities."

He estimated the total rubble from bombardment and explosions at 37 million tonnes.

"We are talking about a colossal figure, and this figure is increasing every day," he said. "The latest data indicates that it is already approaching 40 million tonnes."

The UN official also said "72 percent of all residential buildings have been completely or partially destroyed".

"Reconstruction must be planned carefully, efficiently and with extreme flexibility because we do not know how the war will end" and what type of post-war governance will be established in the Gaza Strip.

Nearly seven months into Israel's war on Gaza, the United Nations Mine Action Service (UNMAS) said on Wednesday that the coastal territory is filled with more debris and rubble than Ukraine.

UNMAS estimated the amount of debris in the Gaza Strip at 37 million tonnes in mid-April, or 300 kilogrammes per square metre.

"Gaza has more rubble than Ukraine, and to put that in perspective, the Ukrainian front line is 600 miles (nearly 1,000 kilometres) long, and Gaza is 25 miles (40 km) long," said Mungo Birch, head of the UNMAS programme in the Palestinian territories.

A separate report released Thursday by the UN revealed that if the war in Gaza stopped today, it would still take until 2040 to rebuild all the homes that have been destroyed from Israel’s relentless bombardment and ground incursions into the territory.

“Every additional day that this war continues is exacting huge and compounding costs to Gazans and all Palestinians” said United Nations Development Programme Administrator Achim Steiner.

At least 370,000 housing units in Gaza have been damaged, including 79,000 destroyed completely, according to the new report by the UNDP and the Economic and Social Commission for Western Asia, which details how Israel’s assault has devastated the economy of the Palestinian territories, and how the impact will increase the longer the conflict goes on.

In an earlier report documenting the destruction of Gaza, it was revealed that Israel's airstrikes and bombardment from 7 October 2023 through 9 March 2024 have resulted in the destruction or damage of an estimated 157,200 buildings -- a whopping 55 percent of all buildings in the strip.

Israel's war on Gaza has killed at least 34,596 people, since 7 October, mostly women and children, according to the Gaza health ministry.

Israel's siege has pushed more than half of the population to the brink of famine, with people in north Gaza already living under "famine-like conditions."