Israel has launched its strongest attack on Gaza so far overnight, shutting down the strip’s only power plant and sending the death toll soaring to 1,175.

The strikes come a day after Israeli Prime Minister Benjamin Netanyahu warned of a “prolonged” campaign against Hamas, the military group in Gaza, according to a New York Post report.

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Diplomatic efforts to end the bloodshed have fallen on deaf ears, with several attempts at ceasefires failing to take hold.

But Yasser Abed Rabbo, secretary general of the Palestine Liberation Organisation, said after consultations Palestine may be willing to agree to a “humanitarian truce for 24 hours”.

A joint delegation headed by Palestinian president Mahmud Abbas would travel to Cairo to take the next step, he added, although there was no immediate confirmation of the plan from Hamas.

The Israeli offensive, which began on July 8 to end Hamas rocket attacks on the Jewish state, has killed more than 1100 Palestinians – mostly civilians according to the United Nations – while 56 lives have been lost on the Israeli side, all but three of them soldiers.

The view from my room. #Gaza‘s port on fire. Blast so intense our hotel shook. Some windows blown in. pic.twitter.com/xK1imYlm5x

— Imtiaz Tyab (@ImtiazTyabAJE) July 29, 2014

Or Monday night, a deluge of bombs rained down on Gaza, after an uneasy truce to mark the end of the Muslim holy month of Ramadan and the Eid al-Fitr holiday.

Shells fired from tanks struck Gaza’s biggest power plant, causing damage and a fire, bringing it grinding to a halt, a senior official with the electricity authority said.

We are sitting in darkness bc th power is off, flares r lightening up th area just like it’s midday,we’re just hearin bombs,drones,f16s#Gaza

— Guess what (@Farah_Gazan) July 28, 2014

The World Health Organisation now estimates more than 215,000 people, or one Gazan in every eight, have fled their homes in the overcrowded territory.

The surge in violence drew increasingly urgent international demands for an end to hostilities.

“In the name of humanity, the violence must stop,” UN chief Ban Ki-moon said on Monday.

But the calls went unheeded, with Israeli Prime Minister Benjamin Netanyahu warning it would be “a lengthy campaign” that would go on until troops destroyed cross-border tunnels used for staging attacks on Israel.

– with AAP