Plumes of smoke rose Thursday over the northern Gaza Strip, where Israel's military urged civilians to evacuate, as rescuers said Israeli strikes across the territory killed more than 50 people.

The latest evacuation warning for parts of Gaza City and neighbouring areas came hours after the United Nations said it had begun distributing around 90 truckloads of aid in Gaza -- the first such delivery since Israel imposed a total blockade on 2 March.

The World Food Programme (WFP) later said a "handful of bakeries" had resumed making and distributing bread, while the United Nations said some trucks were "intercepted" by residents.

Under global pressure to lift the blockade and halt a newly expanded offensive, Israeli Prime Minister Benjamin Netanyahu said he was open to a "temporary ceasefire", but reaffirmed the military aimed to bring all of Gaza under its control.

In an Arabic-language statement on Thursday, the military said it was acting "with intense force" in 14 areas of the northern Gaza Strip, including parts of Gaza City and the Jabalia refugee camp.