The body's human rights office said Israeli forces "may have systematically violated the principles of distinction, proportionality and precautions in attack".

This claim is based on the assessment of six Israeli attacks that caused a high number of casualties and destruction of civilian infrastructure in Gaza between 7 October and 2 December.

Volker Turk, the UN high commissioner for human rights, said the requirement to pick methods avoiding or at least minimising civilian harm "appears to have been consistently violated".

A spokesperson for the UN office said it is "yet to see credible and transparent investigations", adding there would be a need for "international action in this regard" if Israel fails to investigate.

Israel's permanent mission to the UN in Geneva described the analysis as "factually, legally and methodologically flawed".

Israel's offensive - launched following Hamas's deadly 7 October assault - has killed more than 37,000 Palestinians, according to the authorities in Gaza.

Israeli Prime Minister Benjamin Netanyahu on Tuesday claimed the US is withholding weapons and suggested this has slowed the offensive in the south Gaza city of Rafah.

"It's inconceivable that in the past few months, the administration has been withholding weapons and ammunitions to Israel," he said.

"Give us the tools and we'll finish the job a lot faster."

President Joe Biden has delayed delivering certain heavy bombs to Israel since May over concerns about the killing of civilians in Gaza.

The US has gone to lengths to avoid any suggestion that Israeli forces have crossed a red line, which would trigger a more sweeping ban on arms transfers.

Despite international pressure, Israeli forces advanced deeper into western Rafah on Wednesday, according to Palestinian residents and medics.

They claim eight people have been killed, with residents reporting tanks moving into five neighbourhoods after midnight and heavy shelling and gunfire hitting tents in the al Mawasi area.

While concerns over the dire humanitarian conditions in Gaza continue, tensions on the northern Israeli border with Lebanon are growing.

Iran-backed Hezbollah has been trading fire with Israel for the past eight months and last week fired its largest volleys of rockets and drones so far at Israeli military sites.

That came after an Israeli strike killed the most senior commander yet.

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Israel's foreign minister Israel Katz warned on Tuesday a decision on an all-out war with Lebanese militants Hezbollah is coming soon.

"In an all-out war, Hezbollah will be destroyed and Lebanon will be severely beaten," he added.

Hezbollah says it will not halt its attacks unless there is a ceasefire in Gaza.

The conflict has already involved the US military, which has been conducting strikes on Yemen's Houthi group in response to repeated attacks on naval traffic.