Israel signaled intent to encircle Gaza's main city on Sunday, publishing pictures of battle tanks on the Palestinian enclave's western coast 48 hours after ordering expanded ground incursions across its eastern border.

Israel's self-declared "second phase" of a three-week war against Iranian-backed Hamas militants had initially been kept from public view, with forces moving under darkness and a telecommunications blackout cutting off Palestinians.

The phone and internet cuts appeared to be easing on Sunday, according to Gaza residents. But they have severely hampered rescue operations for casualties of Israeli barrages wreaking destruction, especially on northern Gaza City, on Hamas' government and command center sites.

As well as the Israeli military's pictures of tanks, some images online appeared to show Israeli soldiers waving an Israeli flag deep inside Gaza.

Hamas said it was firing mortars against Israeli forces in north Gaza and had hit Israeli tanks with missiles, belittling reports of deep advances by its enemy.

"Israel cut us off from the world in order to wipe us out, but we are hearing the sounds of explosions and we are proud the resistance fighters have stopped them at meters distance," said Shaban Ahmed, a public servant who stayed in Gaza City despite an Israeli warning to evacuate south.

Ahmed said he only found out on Sunday that his cousin had died in an air strike two days previously due to the blackout.

Israeli Defense Force (IDF) fighter jets struck over 450 Hamas targets, including operational command centers, look-out posts and anti-tank missile launch posts, in the last 24 hours, the military said on Sunday.

It said several gunmen emerged from a tunnel near Israel's border and were killed or wounded in a clash with troops.

"We are gradually expanding the ground activity and the scope of our forces in the Gaza Strip," said IDF spokesperson Rear Admiral Daniel Hagari.

Israel has tightened its blockade and bombarded Gaza since Hamas gunmen stormed across the border into Israel on October 7, killing at least 1,400 people and taking more than 200 hostages.

The International Criminal Court prosecutor Karim Khan visited the Rafah crossing where he said blocking relief for innocent civilians could constitute a crime and urged Israel to cooperate.

Western countries have generally backed what they say is Israel's right to self-defense. But there has been mounting international outcry for a "humanitarian pause" to allow aid in.

Israel will allow a dramatic increase in aid to Gaza in coming days and Palestinian civilians should head to a "humanitarian zone" in the south of the tiny territory, said Colonel Elad Goren of Cogat, the Israeli Defense Ministry agency that coordinates with the Palestinians.

Medical authorities in the Gaza Strip, which has a population of 2.3 million people, said on Sunday 8,005 people - including 3,324 minors - had been killed.

The Hamas-run Gaza government's media office said 116 medics and 35 journalists have been killed since the conflict erupted.

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Israel 'heads into 2nd stage of war,' regional countries warn against further ground operations