UN special rapporteur for the occupied Palestinian territory Francesca Albanese used a National Press Club address to declare Israel's right to self-defence is "non-existent".
Ms Albanese claimed international law doesn't let a country invoke self-defence when the threat comes from a country it occupies.
"Israel cannot claim the right of self-defence against a threat that emanates from the territory … that is kept under belligerent occupation," she said.
"Israel was allowed to act to establish law and order to repel the attack, neutralise whoever was carrying out the attacks and then proceed with law and order measures … not waging a war."
She called for a ceasefire in the Middle East and for all Israeli hostages held by Hamas after the October 7 attacks to be released, along with an arms embargo and humanitarian corridors to be created.
But Ms Albanese insisted a plan to end the occupation of Palestine was just as important, believing that would ensure another form of resistance doesn't emerge even if Hamas is eliminated.
She took aim at the targeting of a Palestinian refugee camp and labelled it a war crime, arguing that even if it eliminated a Hamas operative, proportionality could not be ensured.
"Let's assume there was one Hamas operative Israel wanted to target and kill - in order to kill that person the lives of hundreds of Palestinians … have been endangered," she said.
"This is clearly not respecting the principle of distinction, for which a military action needs to be proportionate to the military goal and principle of proportion."
Ms Albanese, who has repeatedly condemned Hamas' attacks, argued ending the "Jewish-Israeli dominance" in Palestine would be a "real humanising act".
More than 100 UN staff have been killed in Gaza since October 7, which makes it the most lethal conflict in the organisation's history.
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