The United Nations said Tuesday its satellite analysis agency UNOSAT had determined that 18 percent of Gaza's infrastructure had been destroyed since the outbreak of the Israel-Hamas war, following the unprecedented October 7 attack by the Palestinian militant group.

The estimate is based on an image taken on November 26, the agency said, a 49-percent increase in the total number of structures affected since a previous assessment on November 7.

"As of 26 November 2023, UNOSAT has identified 10,049 destroyed structures, 8,243 severely damaged structures, and 19,087 moderately damaged structures, totalling 37,379 structures affected," it said.

"This corresponds to around 18% of the total structures in the Gaza Strip."

The war began with Hamas's October 7 attacks that killed 1,200 people, mainly civilians, according to Israeli figures, and saw around 240 hostages taken back to Gaza.

Israel has responded with a relentless offensive of air strikes and ground assaults aiming to destroy Hamas that has reduced much of Gaza to rubble, leaving more than 18,000 people dead, mostly civilians, according to the Hamas-run health ministry.

"These findings underscore the urgent need for immediate ceasefire and support to address the growing humanitarian crisis in the Gaza Strip," UNOSAT said. 

"The impact on civilian infrastructures is evident, with thousands of homes and essential facilities being damaged."