ISRAEL’S vicious offensive in Gaza piled up casualties today, with the death toll of Palestinians topping 515 and over 3,600 other victims wounded.

The casualties included over 120 children and at least 85 women.

The UN security council called for an “immediate ceasefire” as Israel continued the air assault on the Gaza Strip, killing 28 members of a single family near the southern border with Egypt.

UN secretary general Ban Ki Moon held talks with regional leaders and called on Israel to exercise “maximum restraint and do far more to protect civilians.”

But Israel made no response and instead appeared to be stepping up the offensive.

Israeli tanks shelled the al-Aqsa hospital in Deir al-Balah in the central Gaza Strip, killing at least five people and wounding another 60, 15 of whom were said to be medical staff.

The third floor of the hospital was hit by at least 12 tank shells.

Shells landed in the administration building, the intensive care unit and the surgery department.

The hospital is the third to be hit by Israeli tank fire since Israel launched its ground offensive in Gaza.

A doctor at the scene of the attack told Al-Jazeera: “We cannot do anything here for our patients, all the patients, all the injured in the emergency department.”

There were no indication that the hospital was used by armed Hamas fighters and hospital administrator Basman Elashi flatly denied that there were any weapons on the premises.

However, Israeli spokesman Mark Regev continued to insist that Hamas used hospitals as military centres.

Palestinian President Mahmoud Abbas described the situation in Gaza as “intolerable” and the Israeli attacks a “crime against humanity.”

Meanwhile, US Secretary of State John Kerry made a renewed push for a ceasefire.

He urged Hamas to accept a ceasefire agreement offered by Egypt that would halt nearly two weeks of fighting.

Cairo’s ceasefire plan is backed by the US and Israel.

But Hamas has already rejected the Egyptian plan.

The UN relief agency in Gaza estimates that 70,000 Palestinians have fled their homes and are seeking shelter in schools and other shelters set up by the United Nations.