Israel warned of “further consequences” after it stopped the entry of all goods and supplies into the Gaza Strip on Sunday, in a move aimed at pressuring Hamas to accept a new proposal to extend the fragile ceasefire.

“Israel will not allow a ceasefire without the release of our hostages,” a statement from Prime Minister Benjamin Netanyahu’s office said. “If Hamas continues its refusal, there will be further consequences.”

Hamas accused Israel of trying to derail the existing ceasefire agreement and said its decision to cut off aid was “cheap extortion, a war crime and a blatant attack” on the truce. Both sides stopped short of saying the ceasefire had ended.

Egypt, who served as a key mediator with the militant group, condemned Israel’s decision to stop aid, accusing it of using “starvation as a weapon.”

Egyptian Foreign Minister Badr Abdelatty on Sunday called for the immediate implementation of the next phase of the Israel-Hamas ceasefire.

Hundreds of aid trucks have entered Gaza daily since the ceasefire began on Jan. 19, and it was unclear what the immediate impact of the aid cutoff would be.

The first phase of the ceasefire, which included a surge in humanitarian assistance for people in Gaza, expired on Saturday.  The two sides have yet to negotiate the second phase, during which Hamas was to release dozens of remaining Israeli hostages in return for an Israeli pullout and a lasting ceasefire.

Netanyahu said that under the existing agreements Israel could resume fighting after the first phase if it believed negotiations were ineffective. He said the ceasefire would only continue if Hamas kept releasing hostages, telling his Cabinet that “there will be no free lunches.” He said Israel was “fully coordinated” with President Trump’s administration.

There was no immediate comment from the United States on the proposal announced by Israel or its decision to cut off aid.

At the same time, Israeli warplanes intensified their activity over Gaza, carrying out airstrikes on areas in Khan Younis and Beit Hanoun, resulting in casualties, CBS News’ team in Gaza reported. Reports indicate that these attacks killed at least two people and injured others, including women and children.

Border crossings into Gaza remain closed, exacerbating the humanitarian crisis in the Gaza Strip.

Earlier Sunday, Israel said a new proposal, which it said came from U.S. Mideast envoy Steve Witkoff, called for extending the ceasefire through Ramadan – the Muslim holy month that began over the weekend – and the Jewish Passover holiday, which ends on April 20.

Under that proposal, Hamas would release half the hostages on the first day and the rest when an agreement is reached on a permanent ceasefire, according to Netanyahu’s office.

Foreign Minister Gideon Saar said Israel was prepared to negotiate over the next phase but insisted on more hostages being freed during the talks. He said Israel had received a side letter from the Biden administration saying there was no automatic transition between the phases of the truce.

“We fulfilled all our commitments (under Phase 1) until the very last day, which was yesterday,” he told a press conference. “Our position is that during negotiations, hostages should be released.”

Hamas warned that any attempt to delay or cancel the ceasefire agreement would have “humanitarian consequences” for the hostages and reiterated that the only way to free them was through implementing the existing deal, which did not specify a timeline for freeing the remaining captives.

Hamas has said it is willing to free the hostages all at once in Phase 2, but only in return for the release of more Palestinian prisoners, a permanent ceasefire and the withdrawal of Israeli forces.

An Egyptian official said Hamas and Egypt would not accept a new proposal aimed at returning the remaining hostages without ending the war. The official noted that the agreement had called on the two sides to begin negotiations over Phase 2 in early February.

The official, who was not authorized to brief media and spoke on condition of anonymity, said mediators were trying to resolve the dispute.

Under the first, six-week phase of the ceasefire, Hamas released 25 Israeli hostages and the bodies of eight others in exchange for the release of nearly 2,000 Palestinians imprisoned by Israel. Israeli forces pulled back from most of Gaza and Israel allowed a surge of humanitarian aid to enter.

Israel imposed a complete siege on Gaza in the opening days of the war and only eased it later under U.S. pressure.

The war began when Hamas-led terrorists stormed into southern Israel on Oct. 7, 2023, killing some 1,200 people, mostly civilians, and taking 251 hostages. The militants are currently holding 59 hostages, 32 of whom are believed to be dead, after releasing most of the rest in two ceasefire agreements.

Israel’s offensive has killed over 48,000 Palestinians, according to Gaza’s Health Ministry. It says more than half of those killed were women and children but does not specify how many of the dead were combatants.

Israeli bombardment and ground operations pounded large areas of the strip to rubble and at the height of the conflict displaced some 90% of the population of 2.3 million Palestinians. The war has left most of Gaza’s population dependent on international aid for food and other essentials.