A UN agency says 500,000 displaced people in the Gaza Strip may head to Rafah, warning that the city is already overcrowded and cannot cope with them.

The UN Relief and Works Agency for Palestine Refugees, or UNRWA, posted comments on social media on Tuesday. The Israeli military has been telling people in the eastern part of Khan Younis, a key city in southern Gaza, to move further south to Rafah for their safety.

The agency said, "The evacuation order has created panic, fear and anxiety to people in Gaza -- many have already been displaced more than once in this war."

Thomas White, the agency's director in the region, estimated that half a million people could be displaced to Rafah. But he said the city will not cope with that much increase in population. He noted that Rafah normally has a population of 280,000 and is already hosting around 470,000 displaced people.

White added that UNRWA is handing out its last 300 tents, but thousands of people are still living outdoors without shelter.

UNRWA says the Israeli military has ordered people to leave their homes in areas where a total of 600,000 people live. The agency says 69 of their shelters are located in those areas.