Prime Minister Benjamin Netanyahu said on Wednesday a wave of deadly overnight strikes on Gaza was "only the beginning" of Israeli action in the Palestinian territory.
"Hamas has already felt the strength of our hand in the past 24 hours. And I want to promise you — and them — this is only the beginning," Netanyahu said in a televised address.
"From now on, negotiations will take place only under fire," he said, adding, "military pressure is essential for the release of additional hostages".
During his address, Netanyahu denied accusations that the resumption of strikes in Gaza was driven by domestic political concerns.
The White House said Israel consulted United States President Donald Trump's administration before launching the strikes, while Israel said the return to fighting was "fully coordinated" with the US.
A US state department spokesperson said: "Hamas bears total responsibility ... for the resumption of hostilities."
'Intolerable level of suffering'
The United Nations and countries around the world condemned the strikes, while the families of Israeli hostages pleaded with Netanyahu to halt the violence, fearing for the fate of their loved ones.
Prime Minister Anthony Albanese also called on Israel and Hamas to "respect the ceasefire and hostage deal" that was previously put in place.
"We don't want to see innocent people suffer; there's already been enormous suffering there," he said.
UN chief António Guterres said Gazans were being subjected to an "intolerable level of suffering" with the strikes.
United Nations Children's Fund spokesperson Rosalia Bollen, speaking to Agence France-Presse 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 said.
Israel's fresh wave of strikes across Gaza on Tuesday ended a weeks-long standoff over extending the ceasefire that largely halted fighting in January and February, with Palestinian health ministry officials reporting at least 400 people killed and hundreds more injured.
Strikes were reported in multiple locations, including northern Gaza, Gaza City, Deir al-Balah, Khan Younis and Rafah in the central and southern areas of the Gaza Strip. Palestinian health ministry officials said many of the dead were children.
The attacks were far wider in scale than the regular series of drone strikes the Israeli military has said it has conducted against individuals or small groups of suspected militants and follow weeks of failed efforts to agree on an extension to the truce. The first of expired on 1 March.
Responding to the strikes, Hamas accused Israel of going after "defenceless civilians" and overturning the ceasefire agreement, leaving the fate of 59 hostages still held in Gaza uncertain.
Negotiating teams from Israel and Hamas had been in Doha as mediators from Egypt and Qatar sought to bridge the gap between the two sides following the end of an initial phase in the ceasefire, which resulted in the release of 33 Israeli hostages and five Thai nationals in Gaza in exchange for some 2,000 Palestinian prisoners and those held under administrative detention.
A family prepares Iftar over a fire in the rubble of their destroyed home during Ramadan in the Jabalia refugee camp, northern Gaza, on Monday. Source: AAP, EPA / Haitham Imad
However, Hamas had been insisting on moving to negotiations for a permanent end to the war and a full withdrawal of Israeli forces from Gaza in accordance with the terms of the original ceasefire agreement.
"We demand that the mediators hold Netanyahu and the Zionist occupation fully responsible for violating and overturning the agreement," the group said.
Each side has accused the other of failing to respect the terms of the January ceasefire, and there were multiple hiccups during the first phase. But until now, a full return to the fighting had been avoided.
and had threatened on numerous occasions to resume fighting if Hamas did not agree to return the hostages it still holds.
After the strikes on Tuesday, Palestinian health authorities and witnesses shared accounts of damage in numerous areas of Gaza where hundreds of thousands are living in makeshift shelters or damaged buildings.
A building in Gaza City, on the northern end of the strip, was hit, and at least three houses were hit in Deir al-Balah in central Gaza. In addition, the strikes hit targets in the southern cities of Khan Younis and Rafah, according to medics and witnesses.
In hospitals strained by 15 months of bombardment, piles of bodies in white plastic sheets smeared with blood could be seen stacked up as casualties were brought in.
Some people were brought to overwhelmed hospitals by private cars.
Much of Gaza now lies in ruins after 15 months of fighting, which escalated around the Gaza Strip, killing some 1,200 people, according to Israeli tallies, and abducting 251 hostages.
Israel's subsequent bombardment of Gaza has killed more than 48,000 people, according to local health authorities, and destroyed much of the housing and infrastructure in the enclave, including the hospital system.
Israel's renewed pressure on Hamas came as tensions flared elsewhere in the Middle East, a major supplier of oil to global markets, which has resulted in the Gaza war spread to Lebanon, Yemen and Iraq.
