Good progress is being made in rolling out a polio vaccine to children in Gaza but a permanent ceasefire in the 11-month waris needed to ease humanitarian suffering, the main U.N. agency for Palestinians said on Wednesday.

UNRWA said that three days into the campaign in areas of central Gaza, around 187,000 children had received the vaccine. The campaign will move to other areas of the Palestinian enclave for the second stage.

The campaign was prompted by the discovery of a case of polio in a baby boy last month, the first in the Gaza Strip for 25 years. Israel and Hamas militants agreed to daily pauses of eight hours in the fighting in pre-specified areas to allow the vaccination program. No violations have been reported.

"Great progress! Every day in the Middle Areas of #Gaza, more children are getting vaccines against #Polio," the head of UNRWA, Philippe Lazzarini, said on X on Wednesday.

"While these polio 'pauses' are giving people some respite, what is urgently needed is a permanent ceasefire, the release of all hostages + the standard flow of humanitarian supplies including medical and hygiene supplies (into Gaza)," he said.

Palestinians say a big reason for the return of polio is the collapse of Gaza's health system and the destruction of most of its hospitals during the war. Israel accuses Hamas of using hospitals for military purposes, something the Islamist group denies.

On Tuesday, COGAT, an Israeli defence ministry agency tasked with coordinating aid deliveries into Palestinian territories, said since the onset of the war, it has facilitated the entry of 282,126 vials of the polio vaccine, enough for 2,821,260 people.

It also said in a statement that approximately 554,512 vials of vaccines have entered the Gaza Strip, enough for 4,973,736 individual vaccines for various diseases and potential epidemics in the territory.

Gaza has around 2.3 million people and is one of the world's most densely populated places.