A top Palestinian official told the International Court of Justice on Monday that Israel was blocking humanitarian aid to Palestinians in Gaza as a "weapon of war", at the start of a week of hearings at the UN's top court.

Israel is not participating at the ICJ but hit back immediately, dismissing the hearings as "part of the systematic persecution and delegitimisation" of the country.

The ICJ is hearing dozens of nations and organisations to draw up a so-called advisory opinion on Israel's humanitarian obligations to Palestinians, more than 50 days into its total blockage on aid entering war-ravaged Gaza.

Top Palestinian official Ammar Hijazi told judges that "all UN-supported bakeries in Gaza have been forced to shut their doors".

"Nine of every 10 Palestinians have no access to safe drinking water. Storage facilities of the UN and other international agencies are empty," added Hijazi.

"These are the facts. Starvation is here. Humanitarian aid is being used as a weapon of war," concluded the Palestinian representative.

Speaking in Jerusalem, Israeli Foreign Minister Gideon Saar said the case in The Hague was "part of a systematic persecution and delegitimisation of Israel".

"It is not Israel that should be on trial. It is the UN and Unrwa," he told reporters, referring to the United Nations aid agency for Palestinian refugees.

Israel has banned Unrwa from operating on Israeli soil, after accusing some of the agency's staff of participating in the Hamas October 7, 2023 attack that sparked the conflict.

Independent investigations say it has not provided evidence for its headline allegation. (AFP)