Tens of thousands of reservists began to report for duty on Tuesday for a new Israeli offensive to seize Gaza City, which Prime Minister Benjamin Netanyahu wants to accelerate despite warnings from senior ranks.

Palestinian health authorities said further Israeli airstrikes and shelling across the Gaza Strip had killed at least 100 people on Tuesday, 35 of them in Gaza City in the enclave's north as Israeli forces girded for the offensive.

Israeli Army Radio said 40,000 reservists would report for duty on Tuesday.