The EU's humanitarian aid chief called Monday for "meaningful" pauses in the fighting in Gaza and urgent deliveries of fuel to keep hospitals working in the territory.

"It is urgent to define and respect humanitarian pauses," Janez Lenarcic, European Commissioner for Crisis Management, said at a meeting of the bloc's foreign ministers in Brussels.

"Fuel needs to get in. As you could see, more than half of the hospitals in the Gaza Strip stopped working, primarily because of lack of fuel, and fuel is desperately needed."

The appeal went out as battles between Israeli and Hamas forces have raged around Gaza's largest hospital, which has become the focus in the five-week-old war.

The Hamas-run health ministry said Monday the hospitals in the centre of the heaviest fighting in north Gaza have been forced out of service amid shortages and the fierce combat.

The EU's 27 countries issued a statement Sunday saying hospitals "must be protected" and condemning Hamas for using the medical facilities and civilians as "human shields".

The bloc demanded "immediate humanitarian pauses" to allow desperately needed aid into the besieged territory.

"These pauses have to be meaningful," Lenarcic said.

"First of all, they have to be announced well in advance of the implementation so organisations can prepare to exploit them. Second, they have to be clearly defined time-wise."

EU foreign policy chief Josep Borrell insisted that "Gaza needs more aid from any point of view".

"Water, fuel, food. This aid is available, is in the border waiting to come in," he said.

The Israeli army is pushing on with its campaign aimed at destroying the Islamist movement whose gunmen it says killed at least 1,200 people, mostly civilians, and took about 240 hostages in the country's worst-ever attack.

But Israel is facing intense international pressure to minimise civilian suffering amid its massive air and ground operation, which Hamas authorities say has killed 11,180 people, including 4,609 children.

Israel said 44 of its troops have been killed in the Gaza offensive.

Luxembourg's foreign minister, Jean Asselborn, said that hospitals in Gaza should not be turned into "battlefields".

"Patients who are in intensive care units have no chance," he said.

"There is no more oxygen, there is no more water, there are no more medicines. So these people are going to die."