Israeli forces besieged two more Gaza hospitals on Sunday, pinning down medical teams under heavy gunfire, the Palestinian Red Crescent said, and Israel said it had captured 480 militants in continued clashes at Gaza's main Al Shifa hospital.

Israeli forces say hospitals in the Palestinian enclave where war has been raging for over five months have frequently been used as strongholds of Hamas militants harbouring bases and weapons. Hames and medical staff deny this.

The Palestinian Red Crescent said one of its staff was killed when Israeli tanks suddenly pushed back into areas around Al-Amal and Nasser hospitals in the southern city of Khan Younis, amid heavy bombardment and gunfire.

Israeli armoured forces sealed off Al-Amal Hospital and carried out extensive bulldozing operations in its vicinity, the Red Crescent said in a statement, adding: "All of our teams are in extreme danger at the moment and are completely immobilised."

It said Israeli forces were now demanding the complete evacuation of staff, patients and displaced people from Al Amal's premises and were firing smoke bombs into the area to try to force out its occupants.

A displaced Palestinian was killed inside the hospital compound after being hit in the head by Israeli fire, the Red Crescent said in an update later in the day.

The Israeli military said its forces were hitting "infrastructure" in Khan Younis used as lairs for numerous militants. Hamas denies using hospitals for military ends and accuses Israel of war crimes against civilian targets.

The health ministry in Hamas-run Gaza said dozens of patients and medical staffers had been detained by Israeli forces at Al Shifa in Gaza City in the enclave's north that has been under Israeli control for a week.

The Hamas-run government media office said Israeli forces had killed five Palestinian doctors during their seven-day-old swoop on Al Shifa.

The Israeli military did not immediately respond to a request for comment on that report. It said earlier that it had killed over 170 gunmen in the raid, which the Palestinian Health Ministry said had also caused the deaths of five patients. (Reuters)