The humanitarian aid allowed into the Gaza Strip is not getting to civilians in need, the United Nations said Friday, urging Israel to fulfil its legal obligations.

"The aid that is getting in is not getting to the people, and that's a major problem," Jens Laerke, spokesman for the UN humanitarian agency OCHA, told a media briefing in Geneva.

He highlighted the role of the Israeli authorities at their Kerem Shalom crossing, the main entry point for aid into the besieged Palestinian territory since the Rafah crossing between Egypt and Gaza was closed by the Israeli military on May 7.

"We continue to insist that Israeli authorities' obligation under the law to facilitate delivery of aid does not stop at the border," said Laerke.

"It does not stop when you drop off just a few metres across the border and then drive away, and then leave it to humanitarians to drive through active combat zones -- which they cannot do -- to pick it up," he said.

"We need that safe and unimpeded access to get to the drop-off point so we can pick it up and get it to people.

"We want all parties to live up to their obligations under the law."

The bloodiest-ever Gaza war was sparked by Hamas's October 7 attack on southern Israel, which resulted in the deaths of 1,189 people, mostly civilians, according to an AFP tally based on Israeli official figures.

Militants also took 252 hostages, 121 of whom remain in Gaza, including 37 the army says are dead.

Israel's retaliatory offensive has killed at least 36,224 people in Gaza, mostly civilians, according to the Hamas-run territory's health ministry.