Mr Biden has repeatedly said the US would oppose an IDF operation in Rafah but when first Israeli tanks were sighted at the Rafah crossing with Egypt, capturing the key site, he made it clear that the assault did not go as far as to cross the red line for Washington.

The State Department report also noted that while Israel has the tools to mitigate civilian casualties, the high civilian death toll in Gaza raised “substantial questions” over the IDF’s enforcement of them. 

“One specific area of concern is the impact of Israel’s military operations on humanitarian actors,” the report stated. 

The report also noted that “Israel has not shared complete information to verify” whether US weapons have been used in specific incidents alleged to have involved human rights law violations. 

Nevertheless, the report found that Israel’s assurances that it would use US arms in accordance with international law were “credible and reliable”.

The United Nations and major aid groups raised the alarm about an even worse humanitarian calamity unfolding in Gaza as the Rafah crossing that processed aid going into the enclave remained shut.

Aid operations would grind to a halt “within days” unless the crossing with Egypt, shut down after Israel captured it on Monday, re-opens, the UN warned.

The UN’s World Food Programme will run out of food for distribution in southern Gaza by Saturday unless more aid arrives, Georgios Petropoulos, an official for the UN Office for the Coordination of Humanitarian Affairs (OCHA) working in Rafah, said.

He said about 30,000 people were leaving Rafah daily in search of safety, but that humanitarian workers had no supplies to help them set up camp in a new location.

Other UN agencies warned about an inevitable human toll of an extended operation in densely populated Rafah.

“For five days, no fuel and virtually no humanitarian aid entered the Gaza Strip, and we are scraping the bottom of the barrel,” Hamish Young, Unicef’s senior emergency coordinator in the Gaza Strip, said.

“Let’s be very clear this will result in children dying. Deaths that can be prevented.”