Israel pressed on Sunday with preparations for a ground offensive in Gaza, after giving Palestinians a little more time to flee northern areas it has vowed to target in response to the deadliest attack in its history.Last week, Hamas fighters gunned down, stabbed and burned to death more than 1,300 people in an attack that Israel has compared to 9/11 in the United States, sparking a massive retaliatory bombing campaign that has killed more than 2,200 in Gaza.Israel has warned around 1.1 million people living in the north of the Palestinian enclave to flee to the south ahead of a ground incursion which the military has indicated will focus on Gaza City, the base of the leadership of the Hamas militant group.The military said Gaza City residents must not delay their departure but a spokesperson said late Saturday they still had time to leave and that the ground offensive would not start on Sunday.Since Friday thousands of Gazans, who cannot leave the enclave as it is blockaded by both Israel and Egypt, have packed what belongings they can into bags and suitcases, to trudge through the rubble-strewn streets.A stream of cars, trucks, three-wheeled vehicles and donkey-drawn carts joined the frantic mass movement south, all loaded with families and their belongings, mattresses, bedding and bags strapped onto the roofs of packed vehicles.The Israeli army announced on Saturday evening that it had found "corpses" of hostages kidnapped by Hamas during last week's surprise assault on Israel without giving further details.A potential Israeli ground invasion has also increased fears for the safety of the 150 hostages, including foreigners, that Israel said Hamas seized during its deadly rampage.Hamas has threatened to kill the