"We are also now seeing the breakdown of law and order and the systematic armed looting of our supplies by local gangs," the UN's Tom Fletcher said on Monday during a visit to the Middle East.
It was almost impossible to get even a fraction of the necessary aid into the embattled Palestinian territory, he said, and warned that living conditions in the coastal strip were almost unbearable.
The north of the Gaza Strip has been virtually under siege for more than two months and the United Nations says there is a risk of famine there.
Nearly two million people living in Gaza are at risk of famine. (AP PHOTO)
Since October 6, Israel has rejected more than 100 requests for permission to allow UN aid deliveries, said Fletcher, who heads the UN Office for the Co-ordination of Humanitarian Affairs (OCHA).
Israel was continuing its attacks in densely populated areas with devastating consequences, he said.
"The sustained intensity of violence means that there is nowhere that civilians in Gaza are safe."
"Schools, hospitals and civilian infrastructure have been reduced to rubble."
Israel insists that enough aid is reaching the Gaza Strip, but says the UN is unable to distribute it.
According to international legal opinion - for example, that of the International Court of Justice - the Gaza Strip is occupied territory and Israel is therefore responsible for maintaining order there.
The International Committee of the Red Cross says Israel has a duty to ensure people are provided with everything they need.
However, Israel no longer sees itself as an occupying power because its military withdrew from the Gaza Strip in 2005.
Israel has been fighting against the Palestinian militant Hamas movement in the Gaza Strip since the massacre in Israel led by the group on October 7, 2023, in which 1200 people were killed and more than 250 abducted.
The ensuing conflict has wreaked destruction on the coastal strip and and killed more than 45,200 people according to the Palestinian authorities.
The Israeli military said three soldiers were killed in northern Gaza on Monday after an explosion at a weapons and ammunition depot belonging to the Palestinian militant group Hamas.
The men, aged between 21 and 22, were killed instantly by the massive detonation in Beit Hanoun, the Israel Defense Forces (IDF) said.
Investigators are probing whether the weapons cache was remotely detonated by Hamas fighters.
The number of soldiers killed in the wars in Gaza and against the Hezbollah militia is now 821, according to an Israeli military count.
Meanwhile, the IDF announced that it killed a high-ranking member of Hamas on Saturday.
Tharewat al-Beik was the head of Hamas' internal security department, which was also responsible for protecting the Hamas leadership.
According to local sources, however, al-Beik was the chairman of the government committee for the Legislative Council.
He was killed along with another important Hamas member when a rocket hit his car in Jabalia in northern Gaza.
Hamas has not confirmed the deaths.
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