Israeli forces pushed deep into the ruins of Gaza’s northern edge on Monday to recapture an area where they had claimed to have defeated Hamas months ago, while at the opposite end of the enclave tanks and troops pushed across a highway into Rafah.

With some of the most intense fighting for weeks now taking place on both the northern and southern edges of Gaza, hundreds of thousands of Palestinians have again taken flight, and aid groups warn that a humanitarian crisis could sharply worsen.

Israel described its latest return to the north, where it pulled out most of its troops five months ago, as part of a “mop-up” stage of the war to prevent fighters from returning, and said such operations had always been part of its plan.

In Jabalia, the biggest of Gaza’s eight camps built 75 years ago to house Palestinian refugees, tanks pushed towards the heart of the district. Residents said tank shells were landing at the centre of the camp and air strikes had destroyed clusters of houses.