Israeli tank shellfire killed at least 45 Palestinians as they awaited aid trucks in Khan Younis in the southern Gaza Strip, the territory's health ministry said, adding that dozens of others were wounded.

Israel's military campaign since has killed nearly 55,000 Palestinians, most of them civilians, according to health authorities in Gaza, and flattened much of the densely populated strip. Most of the population is displaced, and widespread malnutrition is a significant concern.

The UN human rights chief said Israel's "means and methods of warfare" were inflicting "horrifying, unconscionable suffering".