The UN General Assembly, the high point of the international diplomatic calendar, comes after Lebanese authorities said Israeli strikes had killed 558 people -- 50 of them children.

"Full-scale war is not in anyone's interest. Even though the situation has escalated, a diplomatic solution is still possible," US President Joe Biden said in his farewell address to the global body.

"In fact, it remains the only path to lasting security to allow the residents from both countries to return to their homes on the border safely," Biden said ahead of an emergency UN Security Council session on Lebanon planned for Wednesday. 

Biden's remarks drew disappointment from Lebanon's foreign minister Abdullah Bou Habib who said they were "not promising" and "would not solve the Lebanese problem," as he estimated that the number of people displaced by Israel's strikes has likely soared to reach half a million.

"We should all be alarmed by the escalation. Lebanon is at the brink," UN Secretary-General Antonio Guterres said when he opened the gathering.

Israel's ambassador to the UN Danny Danon said his country was "not eager" for a ground invasion of Lebanon.

"We don't want to send our boys to fight in a foreign country," he said.

It is unclear what progress can be made to defuse the situation in Lebanon, with efforts to broker a ceasefire in Gaza -- which Israel has relentlessly pounded since October 2023 -- coming to nothing.

Biden on Tuesday pushed again for an elusive ceasefire between Israel and Hamas, telling the global body it was time to "end this war."

Mediator Qatar accused Israel of obstructing Gaza ceasefire talks, with Emir Sheikh Tamim bin Hamad Al-Thani saying "there is no Israeli partner for peace" under the government of Benjamin Netanyahu.

But he added: "We will continue our efforts of mediation to resolve the disputes through peaceful means." 

Turkish President Recep Tayyip Erdogan accused Israel of dragging the entire region "into war."

"Not only children but also the UN system is dying in Gaza," Erdogan said in a scathing speech.

Guterres cautioned against "the possibility of transforming Lebanon (into) another Gaza," calling the situation in the Palestinian territory a "non-stop nightmare."

European Council President Charles Michel said that Israel had the right to exist and defend itself but without inflicting "collective punishment" on civilians living in areas targeted by its military.

President Masoud Pezeshkian of Iran -- which backs Hezbollah in Lebanon and Hamas in Gaza -- condemned "senseless and incomprehensible" inaction by the UN against Israel. 

British foreign minister David Lammy also sounded the alarm over the escalating violence in Lebanon.

"I am very worried about the risk of escalation, and this breaking into a wider regional conflict," he told AFP as Britain announced it was deploying military units to Cyprus to assist with any evacuation of its citizens from Lebanon.

Responding to criticism of Israel, Danon called the General Assembly debate an "annual charade of hypocrisy."

Since last year's annual gathering, when Sudan's civil war and Russia's Ukraine invasion dominated, the world has faced an explosion of crises.

The October 7 attack by Palestinian group Hamas on Israel resulted in the deaths of 1,205 people and prompted a military response in Gaza that authorities say has killed at least 41,467 people.

Militants also seized 251 hostages, 97 of whom are still held in Gaza, including 33 the Israeli military says are dead.

Violence has raged across multiple fronts in the Middle East since the crisis erupted, with the conflict exposing deep divisions at the UN.

Palestinian President Mahmud Abbas took his seat alongside the Palestinian delegation, placed in alphabetical order in the General Assembly for the first time on Tuesday after the delegation received upgraded privileges in May.

At the rostrum, Jordan's King Abdullah II on Tuesday ruled out the forced displacement by Israel of Palestinians to his country, which he said would be a "war crime."

Ukraine was also on the agenda Tuesday with President Volodymyr Zelensky addressing a UN Security Council meeting on the Russian invasion.

"Russia can only be forced into peace, and that is exactly what's needed -- forcing Russia into peace," Zelensky said.