Israel has vowed to "destroy" Gaza City unless Hamas agrees to three of the country's demands in a major ultimatum.
The country has demanded Hamas disarm, release all remaining hostages and end the conflict on Jerusalem's terms.
Israeli Defence Minister Israel Katz wrote on social media: "Soon, the gates of hell will open upon the heads of Hamas's murderers and rapists in Gaza - until they agree to Israel's conditions for ending the war, primarily the release of all hostages and their disarmament."
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"If they do not agree, Gaza, the capital of Hamas, will become Rafah and Beit Hanoun."
Rafah and Beit Hanoun were two cities in Gaza destroyed by Israeli forces during the longstanding conflict in the Middle East.
Prime Minister Benjamin Netanyahu confirmed he had ordered immediate negotiations aimed at freeing all the remaining Israeli hostages as he ordered the invasion of Gaza City, which has a population of around half a million.
Speaking to world media, Netanyahu said: "Given Hamas's refusal to lay down its arms. Israel has no choice but to finish the job and complete the defeat of Hamas.
"And again, contrary to false claims, our policy throughout the war has been to prevent a humanitarian crisis. While Hamas's policy has been to create it."
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Israel has vowed to 'destroy' Gaza City unless Hamas agrees to disarm, release all hostages and end the conflict on Jerusalem's terms in a final ultimatum
|REUTERS
The plans to begin a new phase of military operations in densely populated areas of the city, where famine has now officially been confirmed by the Integrated Food Security Phase Classification, were approved by the Israeli Defence Minister on Wednesday.
These included a wide-ranging call-up for as many as 60,000 IDF reservists.
Sir Keir had previously condemned the invasion and urged Israel to reconsider its decision "to further escalate its offensive in Gaza".
In a statement, he said: "This action will do nothing to bring an end to this conflict or to help secure the release of the hostages. It will only bring more bloodshed."
Smoke rises following an Israeli strike in Gaza City
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Israeli Defence Minister Israel Katz vowed to destroy Gaza unless demands are met
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The Prime Minister added: "What we need is a ceasefire, a surge in humanitarian aid, the release of all hostages by Hamas and a negotiated solution.
"Hamas can play no part in the future of Gaza and must leave as well as disarm.
"Our message is clear: a diplomatic solution is possible, but both parties must step away from the path of destruction."
The Israeli Prime Minister has since blasted Sir Keir Starmer's "weak" and "shameful" plans to recognise the state of Palestine once again.
Palestinians wait to receive food from a charity kitchen
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Mr Netanyahu laid into his British counterpart and issued a dire warning over his response to Israel's military activity in Gaza to boot.
He said: "They [Hamas] commit the greatest savagery against Jews since the Holocaust, and the Prime Minister of Britain says we will reward you with a de facto state which is committed openly to repeating the October 7 massacre over and over and over again."
Britain followed in France's steps to recognise a Palestinian state in September, with Canada and Australia set to follow suit.
The UK Government has been accused of rewading Hamas after its conditions on a Palestinian state relied on Israel meeting certain conditions, including agreeing to a ceasefire in Gaza and reviving the prospect of a two-state solution.