CAIRO/JERUSALEM — The Israeli military said on Wednesday its forces have resumed ground operations in the central and southern Gaza Strip, as a second day of airstrikes killed at least 38 Palestinians, according to local health workers, with another 70 killed overnight.

The renewed ground operations come a day after the Israeli air force killed more than 400 Palestinians in one of the deadliest episodes since the beginning of the conflict in October 2023, shattering a cease-fire that had largely held since January.

The Israeli military said its operations have extended Israel's control over the Netzarim Corridor, which bisects Gaza, and were a "focused" manoeuvre aimed at creating a partial buffer zone between the north and the south of the enclave.

The United Nations said an Israeli airstrike had killed a foreign staffer and wounded five workers at the site of a U.N. headquarters in central Gaza City on Wednesday. But Israel denied this, saying it had hit a Hamas site, where it had detected preparations for firing into Israeli territory.

Jorge Moreira da Silva, executive director of the U.N. Office for Project Services, said: "Israel knew that this was a U.N. premises, that people were living, staying and working there, it is a compound. It is a very well-known place."

U.N. Secretary-General Antonio Guterres called for a full investigation and condemned all attacks on U.N. personnel. In a statement he said the strike brought to at least 280 the number of U.N. colleagues killed in Gaza since October 7, 2023.

In Sofia, the foreign ministry said a Bulgarian working for the U.N. died on Wednesday in Gaza, citing preliminary information. It was not immediately clear if the Bulgarian was the foreign U.N. staffer killed in Gaza.

Israel, which has vowed to eradicate Hamas, said its latest onslaught was "just the beginning."

Trading blame

In the latest violence, local health workers said an Israeli airstrike killed four people and wounded 10 others in a house in the northern Gaza Strip town of Beit Hanoun, where the army renewed evacuation orders to residents earlier on Wednesday.

In Beit Lahiya, a new Israeli airstrike killed 14 people at a mourning tent, medics said.

Israel and Hamas accuse each other of breaching the truce, which had offered a respite for Gaza's 2.3 million residents after 17 months of war that has reduced the enclave to rubble and forced most of its population to evacuate multiple times.

The Israeli campaign has killed more than 49,000 people in Gaza, Palestinian health authorities say, and Israel's refusal in early March not to allow any supplies of any kind from any source enter the strip has deepened the humanitarian crisis with shortages of food, fuel and water.

Israel has accused Hamas of using Palestinian civilians as human shields. Hamas denies this and accuses Israel of indiscriminate bombings.

The war — the most devastating episode in decades of Israel-Palestinian conflict — was triggered by a Hamas-led attack on southern Israel on Oct. 7, 2023, which resulted in the deaths of around 1,200 people and during which Palestinian armed groups took about 250 hostages, according to Israeli tallies.

Prime Minister Benjamin Netanyahu's decision to resume bombardments has triggered protests in Israel as 59 hostages are still held in Gaza, with 24 of them believed to be still alive.

A coalition of hostage families and protesters against Netanyahu's moves against the judiciary and other parts of the security establishment has regrouped and accuses the prime minister of using the war for political ends.

Palestinian medics said Israeli tank shelling on the main north-south Salahuddin Road killed one Palestinian and wounded others.

Hamas spokesperson Abdel-Latif Al-Qanoua told Reuters the closure of the Salahuddin Road was a "total coup" against the cease-fire agreement and a tightening of the blockade on Gaza.

He renewed his group's interest in concluding the three-phased cease-fire agreement and would welcome any proposal "as long as it is based on launching negotiation on the second phase and a complete end to the war in Gaza."

Earlier on Wednesday, the Israeli army dropped leaflets in the northern and southern Gaza Strip, once again ordering residents to evacuate their homes.

'Force you have not seen yet'

Defence Minister Israel Katz issued a video statement warning Gaza residents that evacuation from combat zones would begin shortly.

He said airstrikes were "only the first step" and if the hostages were not released, "Israel will act with force you have not yet seen."

The renewed violence was condemned by Western nations, including France and Germany, as well as Qatar and Egypt, which had been acting as mediators in the ceasefire negotiations.

Israel and Western powers do not want Hamas to play any role in the enclave when the war is over.

Arab nations drew up a plan for peace and reconstruction in Gaza after a proposal from U.S. President Donald Trump to resettle Palestinians and turn it into a "Riviera" of the Middle East triggered outrage in the region. However, the plan has not gained traction.

European Union foreign policy chief Kaja Kallas said on Wednesday she told Israeli Foreign Minister Gideon Saar that the situation in Gaza was "unacceptable."

Jordan's King Abdullah called for the cease-fire to be restored and for aid flows to resume. "Israel's resumption of attacks on Gaza is an extremely dangerous step that adds further devastation to an already dire humanitarian situation," he said on a visit to Paris for talks with French President Emmanuel Macron.

Dorothy Shea, acting U.S. ambassador to the United Nations, said on Tuesday the blame for the resumption of hostilities "lies solely with Hamas," while the rest of the U.N. Security Council condemned the renewed fighting.

Algeria accused Israel of war crimes and genocide; France called for an immediate end to hostilities; the U.K. said there was no “military solution” to the conflict; China’s representative urged “Israel to renounce its obsession with the use of force”; Russia urged for greater action by the Security Council, linking its inaction to the more than 48,000 deaths in Gaza; Pakistan echoed the sentiment citing concern for the “world order” unless the international community responds.

Reporting by Nidal al-Mughrabi in Cairo. Additional reporting by Jana Choukeir in Dubai, Lili Bayer in Brussels, Rachel More in Berlin and James Mackenzie in Jerusalem; Writing by Michael Georgy; Editing by Sharon Singleton and Angus MacSwan