The Israeli military and Palestinian militant group Hamas agreed to three separate, zoned three-day pauses in fighting in the Gaza Strip to allow for the vaccination of some 640,000 children against polio, a senior World Health Organization official said Thursday.

The vaccination campaign is due to start Sunday, said Rik Peeperkorn, the WHO's senior official for the Palestinian territories. He said the agreement was for the pauses to take place between 6 a.m. and 3 p.m. local time.

Peeperkorn said the campaign will start in central Gaza with a three-day pause in fighting, then move to southern Gaza, where there would be another three-day pause, followed by northern Gaza. Peeperkorn added that there was an agreement to extend the humanitarian pause in each zone to a fourth day if needed.

The WHO confirmed on Aug. 23 that at least one baby was paralyzed by the type 2 polio virus, the first such case in the territory in 25 years. The U.N. Security Council will meet later on Thursday on the humanitarian situation in Gaza.

The Israeli military's humanitarian unit (COGAT) said Wednesday that the vaccination campaign would be conducted in coordination with the Israeli military "as part of the routine humanitarian pauses that will allow the population to reach the medical centers where the vaccinations will be administered."

The latest bloodshed in the decades-old Israeli-Palestinian conflict was triggered on Oct. 7 when Palestinian Islamist group Hamas attacked Israel, killing 1,200 and taking about 250 hostages, according to Israeli tallies.

Israel's subsequent assault on the Hamas-governed enclave has since killed over 40,000 Palestinians, according to the local health ministry, while also displacing nearly the entire population of 2.3 million, causing a hunger crisis and leading to genocide allegations at the World Court that Israel denies.