Hamas has advised Palestinians to remain in their residences following the extensive evacuation directives issued by Israel in Gaza.

The Hamas Authority for Refugee Affairs on Friday called on residents of the north of the territory to "remain steadfast in your homes and to stand firm in the face of this disgusting psychological war waged by the occupation."

Israel's military earlier had ordered the evacuation of 1 million civilians from northern Gaza amid preparations for a threatened ground offensive aimed at crushing Hamas.

Israel Defense Forces (IDF) spokesperson Jonathan Conricus said the military sent residents of Gaza City a message telling them to evacuate "from their homes southward for their own safety and protection."

Observers believe that a ground offensive by Israel may be imminent in the Gaza Strip. The Israeli army is "waiting to see what the political leadership decides," army spokesperson Richard Hecht said on Thursday. "We are preparing for a ground maneuver if it is decided."

More than 1,530 Palestinians have been killed and more than 6,600 wounded in Israeli attacks, according to the Gaza Health Ministry.

Dozens of fighter jets attacked 750 targets overnight, Israel's military said early Friday.

More than 2 million people live in poor conditions in Gaza, a narrow strip that stretches for about 40 kilometers along the Mediterranean Sea. Gaza is bordered by Israel to the north and east, and Egypt to the south.

According to the U.N., the evacuation ordered by Israel would affect around half the population.

"Team leaders of the U.N. Office of the Coordination of Humanitarian Affairs and the Department of Safety and Security in Gaza were informed by their liaison officers in the Israeli military that the entire population of Gaza north of Wadi Gaza should relocate to southern Gaza within the next 24 hours," U.N. spokesperson Stephane Dujarric told the U.S. news site Axios. "This amounts to approximately 1.1 million people," Dujarric told Axios. "The same order applied to all U.N. staff and those sheltered in U.N. facilities – including schools, health centers and clinics."

"The United Nations considers it impossible for such a movement to take place without devastating humanitarian consequences," Dujarric added, calling for "for any such order, if confirmed, to be rescinded."