Israel pounded the Hamas-run Gaza Strip with air and artillery strikes on Saturday after an intense night of attacks when it said 150 "underground targets" were hit.

No official toll was immediately given, but a Gaza civil defence official told AFP a "large number" of dead was feared from one of the most intense nights of attacks in Israel's war in response to the Hamas attacks on October 7.

Meanwhile, Hamas has pledged to confront Israeli attacks with "full force" after Israel's military widened its air and ground attacks on the Palestinian enclave, suggesting on Saturday that a long promised ground offensive had begun.

Israel has been building up to a ground invasion since Hamas fighters crossed the border on October 7 and killed 1,400 people, mainly civilians, and took 229 hostages, according to Israel.

More than 7,300 people have been killed in retaliatory Israeli strikes on the territory, including about 3,000 children, according to the health ministry in Gaza.

The Hamas-controlled health ministry says that more than 7,300 people have been killed in Gaza, including about 3,000 children.

A thick haze of smoke covered Gaza and southern Israel after the night of heavy bombardment, according to AFP correspondents.

More air raids and artillery shelling were reported after daybreak but less intense than during the night.

The Gaza civil defence official told AFP: "There are a large number of martyrs and a large number of survivors under the rubble, and we cannot reach them," the official said.

Residents told AFP the Indonesian Hospital in Beit Lahia was damaged by a tank shell and there was major damage around Al-Shifa hospital, Gaza's biggest hospital where thousands of people have taken refuge.

The Israeli army has charged that Hamas fighters were using hospitals in Gaza to "wage war" against Israel.

Paramedics said many people were feared dead after an apartment block and nearby houses were destroyed at dawn at the Beach camp.

The armed wing of Hamas, the al-Qassam brigades, said early on Saturday its fighters were clashing with Israeli troops in Gaza's northeastern town of Beit Hanoun and in the central area of Al-Bureij.

"Al-Qassam Brigades and all Palestinian resistance forces are fully prepared to confront the aggression with full force and thwart the incursions," it said.

'Big plan'

Since the October 7 attacks, Israel warned about 1.1 million people in northern Gaza that they should move to the south.

The Israeli military believes the Hamas leadership and its main infrastructure is concentrated in the north.

An unnamed officer quoted by an Israeli military account on X, the former Twitter, said: "We are bombarding Gaza with an intensity that has never been seen before in the Gaza Strip. From the air, from the ground or from the underground -- the IDF (Israeli army) will eliminate every senior or junior terrorist and all Hamas terrorist infrastructure."

Just before the latest strikes, a senior Israeli officer said the raids did not mark the start of the ground invasion.

"When the war starts, we will know it we will hear it, we will see it," said Colonel Golan Vach, head of Israel's search and rescue operation.

"It is going to be lethal and it is going to take time. What you saw in the past two days of small forces movement inside and out of Gaza was for other reasons. Not so much operational but part of the big plan."

More than eight hours of night attacks on the besieged Palestinian territory into the early hours of Saturday rattled windows and shook the ground in Ashkelon 10 kilometres (6.5 miles) from the Gaza border.

Smoke and the pungent smell of burning material filled the air in the city that has been mainly evacuated since the attacks, an AFP correspondent said.

Israeli military jets continued to fly overhead on Saturday and regular concussive booms could be heard coming from Gaza.

Gaza was under an almost complete blackout, with internet and phone services cut for more than 12 hours by Saturday morning. Telecoms firms and the Palestinian Red Crescent Society said it was the result of Israeli bombardments.

Turkey's President Recep Tayyip Erdogan on Saturday called on Israel to "immediately stop this madness" and end its "attacks" on targets in Gaza after Israeli forces intensified strikes on the Palestinian territory.

"The Israeli bombardments on Gaza intensified last night and once again targeted women, children and innocent civilians and worsened the ongoing humanitarian crisis," Erdogan said on X, formerly Twitter.

"Israel must immediately stop this madness and end its attacks."

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