Fierce fighting has been reported in Jabalia in northern Gaza, after the Israeli military went back into areas where it said Hamas had regrouped.
Residents who fled said they had seen tanks advancing towards Jabalia’s refugee camp, which has come under heavy bombardment since Saturday.
Palestinian armed groups also said they were battling troops in the camp.
Meanwhile, the UN has said 360,000 people have fled Rafah, in the south, since an offensive began a week ago.
The Israeli military has ordered the evacuation of the eastern third of the city, which is swollen with more than a million Palestinians taking refuge.
On Sunday, US Secretary of State Antony Blinken warned Israel that a full-scale offensive in Rafah might provoke “anarchy” without eliminating Hamas.
His comments echoed briefings to Israeli media by unnamed senior Israeli military figures, who said Hamas’s resurgence in northern Gaza was due to a lack of a specific plan from Israel’s government for the “day after” the war.
The military scaled down operations in the north in January after declaring that it had “dismantled” Hamas’s battalions there. But that left a power vacuum in which the group has been able to rebuild.
An estimated 300,000 people trapped in the devastated region are also experiencing a “full-blown famine” due to a lack of aid deliveries, according to the head of the World Food Programme.
Residents who were filmed fleeing Jabalia on foot on Monday morning said they had decided to leave after seeing tanks advance into the area.
“We don’t know where to go. We have been displaced from one place to the next,” one woman told Reuters news agency. “We are running in the streets. I saw it with my own eyes. I saw the tank and the bulldozer.”
The military wings of Hamas and Palestinian Islamic Jihad – which are both proscribed as terrorist organisations by Israel, the UK, US and other countries – said their fighters were targeting Israeli forces in and around Jabalia camp with mortars, anti-tank missiles and machine-guns.
Hamas-affiliated Safa news agency also reported clashes between Palestinian armed groups and Israeli tanks east of Jabalia camp’s market, near several UN-run schools which were being used as shelters by civilians.
The official Palestinian news agency Wafa meanwhile reported that two people were killed in Israeli strikes on homes in Jabalia camp on Monday and that a number of other people were killed in a strike in Jabalia town.
It also cited ambulance crews as saying the bodies of 20 civilians had so far been recovered in Jabalia and taken to Kamal Adwan hospital in Beit Lahia. (BBC)