An Israeli evacuation order issued on Friday for parts of Deir al Balah and Khan Younis further shrank the humanitarian area to just 11 percent of Gaza, UN humanitarians said.

The UN Office for the Coordination of Humanitarian Affairs (OCHA) said the order for a six-block area included two within the Israeli-designated humanitarian zones at Al Mawasi in western Khan Younis. More than 120 displacement sites were affected, hosting an estimated 170,000 people.

"Many of the displaced concerned by today's (Friday's) evacuation order had just recently arrived in the area, after having followed earlier evacuation orders," the office said. "OCHA dispatched a small team on the ground and they saw thousands of people on the move, including many children and women. They were moving towards Deir al Balah without clear destination."

"They had to leave in a hurry with nowhere to go being surrounded by death and destruction," OCHA said.

The office said the new order also affected humanitarian facilities, including a World Food Programme warehouse. A major shortage of storage capacity in Gaza has already affected the ability to receive and dispatch assistance.

OCHA said that so far this month, the Israeli military had issued eight evacuation orders affecting tens of thousands of people in Khan Younis and, to a lesser extent, in northern Gaza. The shortage of shelter supplies, including tents and hygiene supplies such as jerry cans and shampoo, and limited access to essential services at arrival sites exacerbated displaced families' conditions.

Also on Friday, UN Secretary-General Antonio Guterres pleaded for a pause in Gaza hostilities for an anti-poliovirus campaign. The World Health Organization and the UN Children's Fund planned the two-round campaign for later this month or in September. The poliovirus was detected about a month ago in Gaza wastewater.