Geneva: Israel's order to evacuate the northern Gaza Strip has triggered "mass displacement" towards the south of the Palestinian enclave, the United Nations said Sunday.
Israel has warned 1.1 million Palestinian civilians to leave northern Gaza and a steady stream of families in overloaded cars, trucks and donkey carts have since headed south.
"Mass displacement from the north to the south of the Gaza Strip has been ongoing since... Friday morning, after Israel ordered residents to evacuate the areas ahead of military operations," the UN's humanitarian agency OCHA said in an update.
"Humanitarian partners report that the number of internally displaced persons (IDPs) has risen significantly over the last 24 hours; however the exact number is unknown."
Beforehand, as of 11:00 pm (2000 GMT) on Thursday, there were 423,378 IDPs in Gaza, OCHA said.
Around 64 percent were being hosted by UNRWA, the UN agency supporting Palestinian refugees, in 102 premises operated as designated emergency shelters.
"Some 33,054 IDPs had taken refuge at 36 public schools," said OCHA.
"It is estimated that over 153,000 IDPs, whose homes have been destroyed or damaged, or have left their homes due to fear, are residing with relatives and neighbours, as well as in other public facilities."
Israeli forces were Sunday readying for a looming Gaza ground invasion aimed at destroying Hamas, the Palestinian Islamist militant group that unleashed the bloodiest attack in the country's history.
In the eight days since Hamas gunmen killed more than 1,300 Israelis in their surprise onslaught, Israel has responded with a devastating bombing campaign that has claimed over 2,300 lives in Gaza.