Backed by tanks, Israeli troops have mounted their first raids on Hamas rocket crews inside Gaza while gathering information on the location of hostages.

The news came as the first official confirmation that Israel has begun its campaign of revenge and pacification six days after Hamas fighters burst through the border in a massive and coordinated land, air and sea offensive.

“We are striking our enemies with unprecedented might,” said Prime Minister Benjamin Netanyahu in a rare statement televised on Friday after the Jewish Sabbath began.

“I emphasise that this is only the beginning.”

While several thousand residents headed south on Friday from northern Gaza, many others said they would stay.

“Death is better than leaving,” said Mohammad, 20, outside a building smashed by an Israeli air strike near the centre of Gaza.

Mosques broadcast the message to ignore Israel’s repeated warnings: “Hold on to your homes. Hold on to your land.”

The United Nations says the Gaza Strip is fast becoming a “hell hole” and is “on the brink of collapse” as it called on Israel to reverse an “impossible” evacuation order for Palestinians.

More than one million residents of northern Gaza were warned to flee within 24 hours to the south ahead of the promised ground offensive by the Israeli army to root out terrorists, destroy their arms caches and networks of underground tunnels.

UN begs for a ceasefire

Reuters has reported that while there was no sign of a mass exodus in progress, the routes south were dotted with people piling their families and possessions into cars or donkey-pulled carts to flee on foot.

The United Nations pleaded with Israel to call off its operation, warning that the relocation order was a “death sentence” which would lead to “unprecedented levels of misery”.

UN relief chief Martin Griffiths asked how such a huge number of people could possibly move across a “densely populated warzone” in just 24 hours.

Making mass movement even more difficult is the shortage of crossing points on the Gaza Wadi river, which neatly divides Gaza into two more or less equal halves.

There is only one major bridge and two much smaller ones, creating a bottleneck for all intent on escaping the Israeli free-fire zone.

The World Health Organisation (WHO) also noted it would be “impossible” to evacuate vulnerable patients from Gaza’s main hospital, which is in the north.

Humanitarian agencies have warned that the people of Gaza, already in a dire situation without power and fuel, were facing the risk of starvation.

Palestinians flee with few possessions on donkey-pulled carts. Photo: Getty

A number of humanitarian agencies have condemned Israel’s evacuation order, amid reports Israel airstrikes had killed people while they were on the move.

Human Rights Watch demanded to know how one million people could leave “with nowhere safe to go”.

“The roads are rubble, fuel is scarce and the main hospital is in the evacuation zone,” it said.

Israel: ‘We will win’

Israel’s army said it had dropped 6,000 bombs between October 7 and 12, the heaviest-ever air strikes on Gaza.

It has also mobilised 300,000 reservists and amassed tanks near the border in response to the Hamas assault.

The military wing of Hamas said the latest air strikes had killed 13 of the captives it brought back from Israel and that it had fired 150 rockets at Israel in response.

The Israeli military pledged to operate “significantly” in coming days.

“We are fighting for our home. We are fighting for our future,” Defence Minister Yoav Gallant said.

“The path will be long but ultimately I promise you we will win.”

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The threats of a ground invasion have conjured up images of the Nakba, the Arabic word for catastrophe that refers to the 1948 war of Israel’s creation that led to their mass dispossession.

Gaza analyst Talal Okal described the Israeli relocation order as an “attempt to push the Palestinian people of Gaza into Nakba”.

“Like they did in 1948 when they pushed people out of historical Palestine by dropping barrels of explosives on their heads, today Israel is repeating this before the eyes of the world and live cameras,” Okal told Reuters.

Hamas militants killed more than 1300 Israelis in their attack on Saturday which triggered the escalation in the decades-long conflict.

Israeli air strikes in response have killed more than 1400 people in Gaza, authorities there said.

The Israeli military told the civilians of Gaza City to “evacuate south for your own safety and the safety of your families and distance yourself from Hamas terrorists who are using you as human shields.”

“Hamas terrorists are hiding in Gaza City inside tunnels underneath houses and inside buildings populated with innocent Gazan civilians,” it added.

Hamas urged Palestinians to ignore the call, describing it as disinformation designed to sow panic and facilitate Israel’s plan to invade and destroy the militant group.

Israel’s printed warnings to head south immediately rain down on Gaza City. Photo: Getty

The United Nations Palestinian refugee agency on Friday described the military call as “horrendous” and said the enclave was rapidly becoming a “hell hole”.

Palestinian President Mahmoud Abbas told US Secretary of State Antony Blinken in Amman that he “rejects the forced displacement” of Palestinians in Gaza, the official Palestinian news agency WAFA reported.

He said such an event would constitute a “second Nakba” adding that humanitarian corridors must be allowed in the blockaded coastal enclave immediately to prevent a humanitarian disaster, the report said.

‘No safe place to go’

“Ordering a million people in Gaza to evacuate, when there’s no safe place to go, is not an effective warning. The roads are rubble, fuel is scarce and the main hospital is in the evacuation zone,” Clive Baldwin, senior legal adviser at Human Rights Watch, said.

Inside Shifa hospital, the largest of Gaza’s 13 public hospitals, a man arrived to check on dozens of relatives and friends who have been brought from the site of a residential building Israel bombed in Beach refugee camp.

“I survived, I don’t know why I survived. It is so that I tell the enemy, America, Europe and the world that this Palestinian people will not be defeated,” the man cried toward reporters.

“They think there will be another displacement, or that we may go to Egypt. Nonsense,” he said before going into the morgue to try and identify dead relatives.

“We are fighting for our future,” Israeli Defence Minister Yoav Gallant says.

Eyad Al-Bozom, spokesman for the Hamas Interior Ministry, urged Arabs everywhere and especially in countries that have borders with Israel to support the people of Gaza.

“We tell the people of northern Gaza and from Gaza City, stay put in your homes, and your places. By carrying out massacres against the civilians, the occupation wants to displace us once again from our land,” he said.

A few of the more than a million Palestinians ordered by Israel to abandon their homes. Photo: Getty

“The 1948 displacement will not happen. We will die and we will not leave,” Bozom said at a news conference held in Shifa hospital in Gaza City.

UN spokesperson Stephane Dujarric said it was impossible for Gazans to heed Israel’s order to move south without “devastating humanitarian consequences”, prompting a rebuke from Israel that the UN should condemn Hamas and support Israel’s right to self-defence.

“The noose around the civilian population in Gaza is tightening. How are 1.1 million people supposed to move across a densely populated war zone in less than 24 hours?” UN aid chief Martin Griffiths wrote on social media.

Blinken’s shuttle diplomacy

Mahmoud Abbas, president of Hamas’ rival, the Palestinian Authority, told US Secretary of State Antony Blinken in Jordan that the forced displacement would constitute a repeat of 1948, when hundreds of thousands of Palestinians fled or were driven from what is now Israel. Most Gazans are descendants of such refugees.

Gaza is one of the most crowded places on earth, and for now there is no way out.

In addition to Israel’s blockade, Egypt has resisted calls to open its border with Gaza.

US Defence Secretary Lloyd Austin on Friday met Israeli Defence Minister Yoav Gallant. Austin said military aid was flowing into Israel but that this was the time for resolve and not revenge.

Gallant said, “The path will be long, but ultimately I promise you we will win.”

Blinken also met King Abdullah in Jordan on Friday as well as Abbas, whose Palestinian Authority exercises limited self-rule in the Israeli-occupied West Bank but lost control of Gaza to Hamas in 2007.

Blinken later flew to Qatar, a US ally with influence among Islamist groups.

-with AAP