A U.N. spokesman said such a movement would turn “what is already a tragedy into a calamitous situation.”

Israel’s military has informed the United Nations that the entire population of northern Gaza should relocate to the southern half of the territory within 24 hours, the U.N. spokesman, Stéphane Dujarric, said late on Thursday night, adding that such a movement — involving over one million people — would lead to “devastating humanitarian consequences.”