The IDF on Tuesday ordered Gaza City residents to evacuate ahead of a new offensive, after Israel warned it would 'raze' the strip if Hamas does not free the hostages it holds.

Residents of the city of one million Palestinians have been expecting an onslaught for weeks, since the Israeli government devised a plan to deal Hamas a fatal blow in what it says are the militant group's last remaining strongholds.

'I say to the residents of Gaza, take this opportunity and listen to me carefully: you have been warned - get out of there!' Israeli Prime Minister Benjamin Netanyahu said.

The evacuation orders caused panic and confusion among residents of the strip's largest urban centre. Some said they would have no choice but to leave for the south, but most said they would stay as no other place was safe.

'Despite the bombardment in the past week, I have resisted leaving, but now I will go to be with my daughter,' said Um Mohammad, a 55-year-old mother of six.