The Israeli military has told the UN that everyone living north of Wadi Gaza should relocate to southern Gaza in the next 24 hours, says a UN spokesperson.
The UN says this amounts to approximately 1.1 million people – about half the population of the entire Gaza Strip. The affected area includes densely populated Gaza City.
The alert was given just before midnight, Gaza and Jerusalem time (23:00 GMT).
“The United Nations considers it impossible for such a movement to take place without devastating humanitarian consequences,” the UN said in a statement.
Israel has been preparing for a ground offensive, gathering soldiers, heavy artillery and tanks on the border of Gaza. It has been launching airstrikes on Gaza since Saturday after Hamas militants’ surprise attack on Israel.