Israel said it had "dismantled" Hamas's military leadership in northern Gaza as its war against the Palestinian group entered its fourth month Sunday, with fears mounting that the conflict could spread into neighboring Lebanon.

Witnesses said Israel carried out air strikes early Sunday in Gaza's main southern city of Khan Yunis, with the official Palestinian news agency Wafa reporting numerous dead and wounded.

Israel's army said late Saturday it had "completed the dismantling of the Hamas military framework in the northern Gaza Strip" and its forces would now focus on central and southern areas of the territory.

The prospect of a wider regional war loomed with army spokesman Daniel Hagari warning that Lebanon's Iran-backed Hezbollah group was "dragging Lebanon into an unnecessary war".

The group fired more than 60 rockets at an Israeli military base on Saturday in response to this week's killing in Beirut of Hamas's deputy leader.

The war in Gaza was triggered by an unprecedented attack on Israel launched by Hamas on 7 October, which resulted in the deaths of around 1,140 people, most of them civilians, according to an AFP tally based on official Israeli figures.

The militants also took around 250 hostages, 132 of whom remain in captivity, according to Israel, including at least 24 believed to have been killed.

In response, Israel is carrying out a relentless bombardment and ground invasion that have killed at least 22,722 people, according to the Hamas-run Gaza health ministry.

Israel's Prime Minister Benjamin Netanyahu vowed that Israel would continue its campaign to "eliminate Hamas, return our hostages, and ensure that Gaza will no longer be a threat to Israel".

Netanyahu was under growing pressure on Saturday with demonstrators gathering in Tel Aviv's Habima Square to call for early elections and the resignation of his government.

"Bibi Netanyahu and all the rest of his idiots are ruining Israel and they are destroying everything we hoped and dreamed of," Shachaf Netzer, 54, told AFP.

"Everybody here wants an election."

AFP correspondents reported Israeli strikes on Saturday in the southern city of Rafah, where hundreds of thousands of people have sought shelter from the fighting.

Victims of the bombardment were brought to the European Hospital in Khan Yunis, where relatives and mourners gathered.

One of them, Mohamed Awad, wept over the body of a 12-year-old boy and counted the deaths in his family. 

"My brother, his wife, his children, his relatives and the brothers of his wife — there are more than 20 martyrs," Awad, a journalist, told AFP.

Civilians in the Hamas-ruled Gaza Strip have borne the brunt of the conflict as the scale of the destruction has triggered mass displacement and a deepening humanitarian crisis.

With swathes of the territory reduced to rubble, UN humanitarian chief Martin Griffiths on Friday said "Gaza has simply become uninhabitable".

The World Health Organization says most of Gaza's 36 hospitals have been put out of action by the fighting while remaining medical facilities face dire shortages.

In Gaza City, bereaved Palestinians reburied bodies exhumed from a cemetery, an AFP video showed.

The footage from the cemetery in the Al-Tuffah neighborhood showed bodies wrapped in bags and laid out on mounds of soil.

Amid a swarm of flies, a few dozen men wearing gloves and surgical masks were busy reburying them.

"We were surprised to see the exhumed bodies," one of the men burying the corpses told AFP.

Top Western diplomats were in the region over the weekend as part of a fresh push to boost the flow of aid into Gaza and address mounting fears of a wider conflict.

US Secretary of State Antony Blinken was in Jordan on Sunday during a Middle East tour that will take him to Israel and the occupied West Bank next week.

"One of the real concerns is the border between Israel and Lebanon, and we want to do everything possible to make sure we see no escalation," he told reporters in Greece, where he stopped before continuing to Jordan.

Blinken was due to hold talks with Jordan's King Abdullah II before heading to Qatar and Abu Dhabi later in the day.

European Union foreign policy chief Josep Borrell on Saturday visited Beirut, where he met a senior figure in Hezbollah's political wing as part of efforts to avoid Lebanon being drawn into the war, an EU source confirmed.

Borrell also held talks with the head of Hezbollah's parliamentary bloc, Mohammad Raad, Lebanese media reported.

"It is imperative to avoid regional escalation in the Middle East. It is absolutely necessary to avoid Lebanon being dragged into a regional conflict," Borrell told a news conference in Beirut.

Borrell said he would go to Saudi Arabia next to discuss "a joint EU-Arab initiative" for peace.

The Hamas-allied Hezbollah movement has been trading near-daily fire with Israeli forces since early October and earlier fired a barrage of dozens of rockets at an Israeli military base in response to the killing of a senior Hamas figure in a suspected Israeli strike in Beirut on Tuesday.

Hezbollah said it had targeted the Israeli military's Meron air control base with 62 missiles in its "initial response" to the killing of Saleh al-Aruri, Hamas's deputy leader, in Beirut.

The Israeli army reported "approximately 40 launches from Lebanon" and said it struck Hezbollah "military sites" in response.