Israel bombarded Gaza and pressed its ground operations today after issuing what it called a "last warning" for Palestinians to return hostages and remove Hamas from power.

Hamas said it fired rockets at Israeli commercial hub Tel Aviv today in its first military response to the growing civilian death toll from Israel's resumption of air and ground operations in Gaza.

Israel said it had closed off the territory's main north-south route as troops expanded the ground operations they resumed on Wednesday.

Gaza's civil defence agency said 504 people had been killed so far in the Israeli assault, including more than 190 children. Its previous death toll was at least 470.

The armed wing of Hamas, the Ezzedine al-Qassam Brigades, said it fired rockets at Tel Aviv in response to Israel's "massacres" of Gaza civilians.

The Israeli army said it intercepted one projectile fired from Gaza and that two others struck an uninhabited area.

After weeks of stalemate, Israel resumed its air campaign early Tuesday with a wave of deadly strikes that drew widespread condemnation.

The offensive shattered a relative calm that had pervaded in the war-ravaged Palestinian territory since a ceasefire took hold on January 19.

At the Indonesian Hospital in northern Gaza, grieving families knelt by the bodies of their loved ones enveloped in blood-stained white shrouds.

"We want a ceasefire! We want a ceasefire!" one of them, Mohammed Hussein, told AFPTV, appealing for the international community to stop the killing.

"We are defenceless Palestinian people," he added.

Today, the Israeli army banned traffic on the territory's main north-south artery.

Palestinians were seen fleeing south along Salaheddin Road near the Nusseirat refugee camp atop donkey-drawn carts piled high with belongings.

"Over the past 24 hours, IDF soldiers have begun a targeted ground operation in the central and southern Gaza Strip in order to expand the security zone between the northern and southern parts," army spokesman Avichay Adraee said on X.

Movement along Salaheddin Road between the north and south of the Gaza Strip is prohibited "for your safety", he said.

"Instead, travel from northern Gaza to the south is possible via the Al-Rashid coastal road," Adraee added, without spelling out whether that meant movement from south to north was banned.

The first stage of the ceasefire expired early this month amid deadlock over next steps.

Israel rejected negotiations for a promised second stage, calling instead for the return of all of its remaining hostages under an extended first stage.

That would have meant delaying talks on a lasting ceasefire, and was rejected by Hamas as an attempt to renegotiate the original deal.

The head of the UN agency for Palestinian refugees (UNRWA) on Thursday deplored "an endless unleashing of the most inhumane ordeals" on the people of Gaza since Israel resumed its military offensive.

"Israeli Forces bombardment continues from air & sea for the third day," Philippe Lazzarini wrote on X. "Under our daily watch, people in Gaza are again & again going through their worst nightmare."

Iran's supreme leader Ayatollah Ali Khamenei called Israel's latest strikes on Gaza a "catastrophic crime" and said the United States "shares responsiblity".

The overall death toll in Gaza since the start of the Israeli offensive stands at 49,617, according to the Hamas-run territory's health ministry.