Israel said its best soldiers were fighting Hamas inside the Gaza Strip on Saturday night, as Benjamin Netanyahu declared that the “second stage” of a long war against the terror group had begun.

Israel’s forces fought fierce street battles against Hamas in northern Gaza using tanks and infantry, with Lt Gen Herzi Halevi, the chief of the general staff of the Israel Defense Forces, saying his troops had killed “hundreds” of terrorists.

But Mr Netanyahu, the Israeli prime minister, said Israel’s campaign to “abolish evil” was “only just beginning”.

“This is a war with multiple stages, today we move to the next one,” Lt Gen Halevi said on Saturday. “The objectives of this war require a ground operation – the best soldiers are now operating in Gaza.”

A larger Israeli military operation against Hamas had been anticipated since it pledged to destroy the group in the wake of the Oct 7 attacks, but it appeared to have been delayed amid fears of a wider regional war involving Iran and its Middle East proxies.

The prime minister and military leaders stopped short of calling the country’s expanded ground offensive in Gaza an invasion, even as they confirmed that troops would remain in the coastal enclave.

Earlier on Saturday, the Israeli military dropped leaflets across Gaza City, which before the war had a population of half a million people, warning civilians to evacuate because it had become “a battlefield”.

“To the residents of the Gaza Strip: The Gaza governorate (Gaza City) has become a battlefield. Shelters in northern Gaza and Gaza governorate are not safe,” read one leaflet in Arabic.

The Israeli army claims Hamas runs an underground headquarters beneath the al-Shifa hospital in Gaza City. Hamas denies that claim.

On Saturday, the families of those held hostage in Gaza urged the government to tell them how it planned to rescue their loved ones as Israeli forces intensified their operations against Hamas.

Mr Netanyahu said it was hoped that the ground offensive would pile pressure on the terrorist group, making the release of its captives more likely.

As Israeli leaders braced for a regional escalation, Eli Cohen, the foreign minister, confirmed that he had recalled diplomats from Turkey, which has been a strong critic of the war on Hamas in Gaza because of the heavy loss of civilian lives.

At a rally in Istanbul earlier on Saturday, Recep Tayyip Erdogan, the Turkish president, likened Israel’s assault on Gaza to the Holocaust and took aim at the country’s Western backers.

“The main culprit behind the massacre unfolding in Gaza is the West,” he told a crowd of hundreds of thousands of supporters.

Israel was facing mounting criticism over the assault from Gulf neighbours, including Saudi Arabia, which before the war had been considering a historic normalisation treaty.

In Egypt, the foreign ministry warned Israel that there would be “grave risks” and “unprecedented humanitarian and security repercussions” if it continued with the ground offensive.

Riyadh said it “condemns and denounces any ground operations carried out by Israel due to the threat they pose to the lives of Palestinian civilians”.

The Pentagon said Lloyd Austin, the US secretary of defence, had spoken to his Israeli counterpart on Saturday and “underscored the importance of protecting civilians” during the next stage of the war. He also raised “his focus on the need for Hamas to release all of the hostages”.

Josep Borrell, the EU foreign policy chief, reiterated calls for an urgent ceasefire, adding that “far too many civilians, including children, have been killed. This is against international humanitarian law”.

But James Cleverly, the Foreign Secretary, resisted calls for a ceasefire, saying: “Calls for a ceasefire in the abstract aren’t going to help the situation – we have consistently sought to bring about pauses to facilitate the inward passage of the humanitarian aid that we are providing, and the release of hostages and the evacuation of British nationals in Gaza.”

Israel insists it is operating within international law and is taking care to avoid civilian deaths.

It has almost completely cut off the internet in Gaza, having placed the enclave under a “total siege” in response to the Oct 7 massacre, isolating it from the rest of the world.

Palestinians in Gaza were using mosque loudspeakers to communicate with each other because of the total internet blackout imposed on Friday night, while ambulances were blindly driving towards explosions as they scrambled to treat the wounded.

Video posted online showed mosques broadcasting emergency messages using speaker systems that would usually deliver the call to prayer. “The communications have been cut,” said one message broadcast over a mosque’s loudspeakers. “All help from the outside world has been cut.”

From the Israeli side of the border, huge fireballs could be seen rising from the sky as Israel launched a torrent of air strikes across the Palestinian enclave.

Aid and media organisations, including The Telegraph, have lost contact with colleagues on the ground, making it difficult to confirm what has taken place in the blockaded strip since Friday night.

Some reports have trickled through, including a dispatch from Rushdi Abualouf, the BBC’s Gaza correspondent, who described the situation as “total chaos”.

“There was a huge bombardment in the north of Gaza strip on a scale we’ve never seen before,” he reported on Saturday. “Huge flames could be seen rising into the sky – it seemed they were using different types of bombs.

“There’s been panic everywhere, even here in Khan Younis, where the bombing was less, as people try to reach family members in other areas to check they are safe, but the phones have been cut off.”

Earlier on Saturday, Israel claimed to have killed Asem Abu Rakaba, the head of the aerial wing of Hamas’s armed forces. Abu Rakaba, who was killed in an air strike, was responsible for Hamas’s air defence as well as its unmanned aerial vehicles and drones.