Gaza City - At least 22 Palestinians have been killed in heavy ground fighting and Israeli air attacks overnight and Tuesday morning, raising the total Palestinian death toll of Israel's Gaza offensive to 573 by late Tuesday morning, health officials said.

The injury toll stands at 2,600, Gaza emergency services chief Mo'aweya Hassanein told reporters in Gaza.

A United Nations agency, UNWRA, said shortly afterwards that three more Palestinian civilians were killed when an Israeli naval shell hit one of its schools in western Gaza City's Beach refugee camp used as a shelter for Palestinian civilians, UNWRA said in a statement sent to reporters. (dpa)