Israeli forces killed at least 48 Palestinians in the past 24 hours across the Gaza Strip as they battled Hamas-led militants, Palestinian officials said on Monday, while medics conducted a second day of polio vaccinations for children in the enclave.

Palestinian and UN officials said more than 80,000 children had been vaccinated in central areas of Gaza on Sunday, the first day of the campaign.

Hamas and Israel have agreed to brief pauses in fighting to allow the campaign to vaccinate some 640,000 children to go ahead. No violations have been reported near vaccination facilities.

Seven Palestinians were killed in two Israeli air strikes on Gaza City, Palestinian officials said on Monday, while two air strikes killed six others in Bureij and Nuseirat, two of the Gaza Strip’s eight historic refugee camps.

The armed wings of Hamas and the Islamic Jihad said fighters had confronted Israeli forces in north, south and in some central area of Gaza with anti-tank rockets and mortar fire.

UNRWA, the UNPalestinian refugee agency, repeated its call on Monday for an immediate ceasefire to help ensure a successful and safe polio vaccination campaign.

“On 1st day only, @UNRWA teams & partners reached around 87,000 children according to @WHO. Efforts are ongoing to provide children with this key vaccine, but what they need most is a #CeasefireNow,” it said on the X social media platform.

Israel and Hamas have continued to trade blame for the failure to conclude a ceasefire, that would end the war, and see the release of Israeli and foreign hostages held in Gaza and many Palestinians jailed in Israel.

Parents continued bringing their infants to be vaccinated at medical facilities on Monday. The WHO says a drop in routine vaccinations in the Occupied Palestinian Territories, including Gaza, has contributed to the re-emergence of polio in the area.