Only about 18 per cent of the Gaza Strip is not now subject to displacement orders or located within militarised zones, Reuters reports, citing the United Nations.

Many Palestinians have been displaced multiple times. Since Israel expanded its military campaign in Gaza City in mid-August, the UN has recorded over 417,000 displacements of people from the north to the south of the enclave.

Israel has urged Gaza City residents to head south. But conditions in southern Gaza are dire, with families crammed into makeshift tents and overstretched services trying to cope with new arrivals, aid agencies say.

The UN human rights office has said any deliberate effort to relocate the population would be tantamount to ethnic cleansing.