• US president asks leaders to prevent "full-scale war" in Lebanon.
•  "Putin's war has failed at its core aim," says Biden about Ukraine.
  
• Biden pushes again for elusive ceasefire between Israel, Hamas.
  

US President Joe Biden makes his final appearance at the UN General Assembly in New York on Tuesday, after dropping out of the race in July and endorsing his vice president as the Democratic nominee, the 81-year-old is not taking any chances.

Prime Minister Shehbaz Sharif also attended the opening session of the 79th UNGA being held today marking the beginning of the annual gathering of world leaders.

Biden asked world leaders to prevent "full-scale war" over Lebanon, as clashes escalated between Israel and Hezbollah, prompting the UN chief to warn of a situation "on the brink."

The UN General Assembly, the high point of the diplomatic calendar, comes as Lebanese authorities say Israeli strikes 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," 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.

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

UN Security Council member France called for an emergency meeting on the crisis, as the EU's top diplomat Josep Borrell warned "we are almost in a full-fledged war."

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

President Masoud Pezeshkian of Iran — which backs both Hezbollah and Hamas — condemned the "senseless and incomprehensible" inaction by the UN against Israel.

Israel's ambassador to the UN, Danny Danon hit back at the UN chief, calling the General Assembly debate an "annual charade of hypocrisy."

"When the UN Secretary General speaks about the release of our hostages, the UN assembly is silent, but when he speaks about the suffering in Gaza, he receives thunderous applause," Danon said.

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.

With Israel's leader Benjamin Netanyahu and Palestinian president Mahmud Abbas expected to address the General Assembly this week, there could be combustible moments.

Abbas took his seat alongside the Palestinian delegation in alphabetical order for the first time after the delegation received upgraded privileges in the assembly in May.

Biden said that Russian President Vladimir "Putin's war has failed at its core aim. He set out to destroy Ukraine, but Ukraine is still free."

It is unclear if the grand diplomatic gathering can achieve anything for the millions mired in conflict, poverty and climate crisis globally.

Additionally, he urged all countries to stop arming rival generals in Sudan, whose bloody war has triggered a major humanitarian crisis.

"The world needs to stop arming the generals. Speak with one voice and tell them: 'Stop tearing your country apart. Stop blocking aid to the Sudanese people. End this war now,'" Biden told the UN General Assembly.