Gaza City, Palestinian Territories — Israeli Prime Minister Benjamin Netanyahu warned on Tuesday that massive overnight strikes on Gaza were "only the beginning" and that future negotiations with Hamas "will take place only under fire".

The strikes, by far the largest since a truce took effect in January, killed more than 400 people across the Gaza Strip, according to the health ministry in the Hamas-run territory.

Netanyahu said in a video statement on Tuesday evening "Hamas has already felt the strength of our arm in the past 24 hours. And I want to promise you — and them — this is only the beginning".

Negotiations have stalled over how to proceed with a ceasefire whose first phase has expired, with Israel and Hamas disagreeing on whether to move to a new phase intended to bring the war to an end.

The Israeli premier said in his address that "from now on, negotiations will take place only under fire," before adding: "Military pressure is essential for the release of additional hostages".

Israel has vowed to keep fighting until the return of all the hostages seized by Palestinian militants during the October 2023 attack that sparked the war.

By Tuesday afternoon, witnesses in Gaza said the attacks had largely stopped, though sporadic bombing continued.

"Today I felt that Gaza is a real hell," said Jihan Nahhal, a 43-year-old woman from Gaza City, adding that some of her relatives were wounded or killed in the strikes.

"Suddenly there were huge explosions, as if it were the first day of the war."

Hamas has not responded militarily so far, and in a statement urged friendly countries to "pressure" the United States to bring to an end the strikes by its ally Israel.

Hugh Lovatt, senior policy fellow at the European Council on Foreign Relations, told AFP that "Hamas does not want to be dragged into another war".

The White House said Israel consulted US President Donald Trump's administration before launching the strikes, while Israel said the return to fighting was "fully coordinated" with Washington.

A State Department spokesperson said that "Hamas bears total responsibility... for the resumption of hostilities".

The United Nations and countries around the world condemned the strikes, while the families of Israeli hostages pleaded with Prime Minister Benjamin Netanyahu to halt the violence, fearing for the fate of their loved ones.

'Complete destruction'

Netanyahu's office said Tuesday's operation was ordered after "Hamas's repeated refusal to release our hostages".

Hamas said Israel had "decided to overturn the ceasefire agreement" brokered by US, Qatari and Egyptian mediators, and warned that the resumption of violence would "impose a death sentence" on the remaining living hostages.

The group's leader, Sami Abu Zuhri, told AFP the aim of the strikes was "to impose a surrender agreement, writing it in the blood of Gaza".

Defence Minister Israel Katz said that "Hamas must understand that the rules of the game have changed", threatening to unleash the Israeli military until the group's "complete destruction" if it did not immediately free the hostages.

Hamas said the head of its government in Gaza, Essam al-Dalis, was among several officials killed.

In the southern Gaza Strip, AFP footage showed people rushing wounded people on stretchers, including young children, to hospital. Bodies covered with white shrouds were also taken to the hospital's mortuary.

'Shocking'

The Gaza health ministry said the bodies of 413 people had been received by hospitals, adding "a number of victims are still under the rubble".

UNICEF spokeswoman Rosalia Bollen, speaking to AFP in southern Gaza, said the deaths include "dozens and dozens of children, with many more children wounded".

Medical facilities that "have already been decimated" by the war were now "overwhelmed", she added.

Families of Israeli hostages rallied in front of Netanyahu's office in Jerusalem, and a campaign group accused the government of causing "the explosion of the ceasefire, which could sacrifice their family members".

Governments in the Middle East, Europe and elsewhere called for the renewed hostilities to end.

"The images of burning tents in refugee camps are shocking. Fleeing children and internally displaced persons must never be used as leverage in negotiations," said Germany's Foreign Minister Annalena Baerbock.

Hamas backer Iran denounced the wave of attacks as a "continuation of the genocide" in the Palestinian territories, while Russia and China warned against escalation.

Egyptian President Abdel Fattah al-Sisi said the strikes were part of "deliberate efforts to make the Gaza Strip uninhabitable and force the Palestinians into displacement".

Trump has floated a proposal to move Palestinians out of Gaza, an idea that was rejected by Palestinians and governments in the region and beyond, but embraced by some Israeli politicians.

Hours after the wave of strikes began, Netanyahu's Likud movement said that a far-right party that had quit the government in January in protest at the Gaza truce would rejoin.

Attack from Yemen

The ceasefire in Gaza took effect on 19 January, largely halting the war triggered by Hamas's 7 October 2023 attack on Israel.

That first phase of the deal ended in early March after numerous exchanges of Israeli hostages and Palestinian prisoners.

But the two sides have been unable to agree on the next steps, with Hamas demanding negotiations for a second phase, which should lead to a lasting ceasefire.

Israel had sought to extend the first phase, cutting off aid and electricity to Gaza over the deadlock.

Hamas's 2023 attack resulted in 1,218 deaths, mostly civilians, while Israel's retaliation in Gaza has killed at least 48,577 people, also mostly civilians, according to figures from the two sides.

Of the 251 hostages seized during the attack, 58 are still in Gaza, including 34 the Israeli military says are dead.

On Tuesday evening, Yemen's Iran-backed Huthi rebels -- have pursued a campaign of attacks in what they say is solidarity with the Palestinians -- launched a missile at Israel, which the military said was intercepted.

(Source: AFP teams in Gaza with Marc Jourdier in Jerusalem, AFP)