Israel is telling everyone in north Gaza – about 1.1 million people – to relocate to the south of the Strip in the next 24 hours.
Meanwhile an Israel Defense Forces spokesman said the military knew it would take longer than that to move everyone, but blamed Hamas for telling people to ignore the order.
Reports say Israel has massed thousands of soldiers on the border ahead of an expected ground offensive into the densely populated enclave.
Meanwhile the United Nations has called on Israel to withdraw the order, warning of “devastating humanitarian consequences”.
Hamas had reportedly kidnapped at least 150 people and took them into Gaza during deadly attacks on Israel at the weekend that killed 1,300 people. Also, More than 1,400 people have allegedly been killed in Gaza since Israel launched retaliatory air strikes, which has continued.