Israel began conducting "ground operations" in the northern Gaza Strip on Thursday following its latest round of attacks that have killed hundreds of people in the enclave, drawing condemnation from the international community which demanded that Israel end violence and return to talks.

A day after launching a new ground campaign in central Gaza, the Israeli military said on Thursday it had begun conducting ground operations in the north of the enclave, along the coastal route in the area of Beit Lahia.

The Israel Defense Forces, or IDF, said its troops aimed to "expand the security zone and to create a partial buffer between northern and southern Gaza".

The Israeli military also said as part of the ground activities, the troops expanded their control further to the center of the Netzarim Corridor.

The renewed offensive shattered a relative calm that had pervaded since the truce took hold in mid-January.

The first stage of the Gaza ceasefire, which largely halted more than 15 months of fighting, expired early this month amid deadlock over next steps.

Israel blames the new fighting on Hamas for refusing to accept revised ceasefire terms. Hamas, in turn, has accused Prime Minister Benjamin Netanyahu of unilaterally upending the truce and putting hostages "at risk of an unknown fate."

Sami Abu Zuhri, a Hamas leader, said the ground operation and advance toward the Netzarim Corridor, cutting off northern Gaza from the south, will completely destroy the cease-fire agreement, the Palestinian Information Center reported.

Hamas spokesman Abdul Latif Al-Qanou said the group was working with negotiators to "spare our people from war permanently", Al Jazeera reported on Thursday.

He also said Hamas remained committed to the original cease-fire framework agreed in January.

Tuesday's first day of resumed airstrikes killed more than 400 Palestinians, one of the deadliest days of the war. At least 510 Palestinians have been killed in the past three days, more than half of them women and children, Khalil Al-Deqran, the spokesman of the territory's health ministry told Reuters. Al Jazeera however, reported the death toll as 506.

During the latest bombardments, five staff members of the United Nations Relief and Works Agency for Palestine Refugees in the Near East, or UNRWA, have been killed in the past few days, the agency's Commissioner-General Philippe Lazzarini said on Thursday.

Lazzarini said he feared the worst was yet to come as Israeli bombardments continue by land and sea, as well as an ongoing ground operation.

The Israeli military, however, said it did not strike a UN compound in Deir al-Balah, and called on media outlets "to act with caution regarding unverified reports".

Various Arab states have denounced Israel's latest aggression.

The Ministerial Committee assigned by the Joint-Arab Islamic Extraordinary Summit released a statement through the Saudi Ministry of Foreign Affairs on Thursday.

It denounced the raids launched by Israeli forces, particularly in areas populated by unarmed civilians.

It also criticized Israel's latest moves as "undermining the efforts to de-escalate tensions and achieving stability in the region".

On Wednesday, thousands of demonstrators rallied in Jerusalem, slamming Netanyahu's government over efforts to remove key security and judicial officials following the collapse of the Gaza cease-fire. They also demanded that the government secure the release of all hostages.

Gokhan Batu, an analyst on Israel studies at the Center for Middle Eastern Studies in Turkiye, told China Daily that it is undeniable the cease-fire was accepted by Israel under pressure from the United States.

"By January, Netanyahu had no intention of agreeing to a ceasefire, as the war's stated objectives remained unfulfilled. The hostages had not been recovered, and Hamas continued to govern Gaza," Batu said.

Although large-scale protests in Israel demanded action to secure the release of hostages, they failed to influence government policy, he noted.

" (US President Donald) Trump's pledge to end wars played a decisive role in this turn of events. However, this promise did not prevent the war from resuming — ironically, it was Trump's own support that facilitated its continuation. Now, in every proposed scenario for Gaza, Palestinians find themselves either as targets or as passive subjects," Batu added.

Effectively, he said, the situation has reverted to the pre-ceasefire status quo.

"The only notable change is the occupant of the White House. While Israel secured the release of around 30 hostages — a significant achievement — the fate of the remaining captives remains uncertain," said Batu.

Agencies and Xinhua contributed to this story.