FILE PHOTO: The United Nations headquarters building is pictured with a UN logo in the Manhattan borough of New York City, New York, U.S., March 1, 2022. REUTERS/Carlo Allegri/ File Photo

By Michelle Nichols

UNITED NATIONS (Reuters) -World leaders gather in New York every September for several days of speeches at the annual United Nations General Assembly, which on Tuesday begins its 80th session.

WHO SPEAKS WHEN?

The United Nations was formed in 1945 with 51 original members and has since grown to 193 members. Leaders of two non-member observer states - known at the U.N. as the Holy See and the State of Palestine - and an observer member, the European Union, can also speak.

It is tradition for Brazil to always be the first member state to speak. This is because in the early years of the world body Brazil stepped up to speak first when other countries were reluctant to do so, say U.N. officials.

As host to the U.N. headquarters in New York, the United States is the second country to address the General Assembly.

From there the list is then based on hierarchy and generally a first come, first served basis. Heads of state speak first, followed by deputy heads of state and crown princes, heads of government, ministers and lower-ranking heads of a delegation.

HOW LONG WILL THEY SPEAK?

Leaders are asked to stick to a voluntary 15-minute time limit.

According to U.N. records, one of the longest speeches made during the opening of a General Assembly was in 1960 by Cuban leader Fidel Castro who spoke for about 4-1/2 hours. Libyan leader Muammar Gaddafi spoke for more than 1-1/2 hours in 2009.

WHAT WILL THEY TALK ABOUT?

Each start of a General Assembly session has a theme. Leaders might briefly refer to the theme before moving on to whatever topic they like.

This year's theme is: "Better together: 80 years and more for peace, development and human rights."

Other topics that leaders are likely to address include:

GAZA. Leaders are gathering as the war between Israel and Hamas militants in the Gaza Strip approaches two years and a humanitarian crisis worsens in the Palestinian enclave, where a global hunger monitor has warned that famine has taken hold and is likely to spread by the end of the month.

Israeli Prime Minister Benjamin Netanyahu - wanted by the International Criminal Court for alleged war crimes and crimes against humanity in Gaza, which Israel denies - is due to address the General Assembly on Friday next week. Israel launched a ground assault on Gaza City on Tuesday.

Palestinian President Mahmoud Abbas will not attend in person - the U.S., a staunch Israeli ally, has said it will not give him a visa. He will likely appear via video.

UKRAINE. Ukrainian President Volodymyr Zelenskiy will be seeking to shore up global support for Kyiv as U.S. President Donald Trump tries to broker an end to the war more than three years after Russia invaded its neighbor. He is due to address the assembly on Wednesday while Russia's Foreign Minister Sergei Lavrov will speak on Saturday.

The U.N. Security Council is due to hold a high-level meeting on Ukraine next week. All eyes will be on the U.S. - at the council and during Trump's General Assembly speech - to see if Washington announces any measures, such as sanctions, to try to get Russian President Vladimir Putin to negotiate with Zelenskiy.

IRAN. Expect last-minute diplomacy in New York over Iran's nuclear program as Tehran seeks to avoid a return of all U.N. Security Council sanctions on the Islamic Republic on September 28. Iranian President Masoud Pezeshkian and Foreign Minister Abbas Araqchi are both expected to be at the United Nations.

SYRIA. A notable debut this year at the U.N. General Assembly will be Syrian President Ahmed al-Sharaa. His Hay'at Tahrir al-Sham group led the rebellion that toppled President Bashar al-Assad in a lightning offensive in December, ending 13 years of civil war.

But HTS, previously known as al-Nusra Front, was al Qaeda's former branch in Syria until it broke ties in 2016. The group and Sharaa remain under U.N. sanctions, but he was given a travel exemption to visit New York from September 21 to 25.

CLIMATE. As the world struggles to limit warming to 1.5 degrees Celsius, leaders of smaller island nations and other states most affected by climate changes are expected to again urge action.

WOMEN. On Monday, a day before speeches begin, leaders will meet to mark the 30th anniversary of a landmark women's rights conference. The 1995 United Nations Fourth World Conference on Women, held in Beijing, is perhaps best known for coining the phrase "women's rights are human rights."

While the theme of the meeting on Monday is to recommit, resource and accelerate implementation of the declaration agreed in 1995, leaders are likely to lament the lack of progress and growing attacks on women's rights. At the Beijing conference 189 nations signed a document calling for the "full and equal participation of women in political, civil, economic, social and cultural life."

SUDAN. The 2-1/2-year-old war in Sudan is likely to be discussed among some leaders next week. The war between the paramilitary Rapid Support Forces and the Sudanese army has created what the United Nations calls the world's worst humanitarian crisis, with widening pockets of famine across the country including in al-Fashir, the capital of North Darfur state.

The United States, the United Arab Emirates, Saudi Arabia and Egypt have called for a three-month humanitarian truce followed by a permanent ceasefire. The so-called "Quad" countries are seen as having the most influence with the warring parties.

U.S.-VENEZUELA TENSIONS. As the United States built up its naval force in the Southern Caribbean and nearby waters late last month, Venezuela complained to U.N. Secretary-General Antonio Guterres. Since then the U.S. military has carried out two deadly strikes on alleged Venezuelan drug cartel vessels in international waters.

The increased tensions are likely to be raised by Venezuela's Foreign Minister Yvan Gil, who is expected to address the General Assembly on Saturday. Venezuelan President Nicolas Maduro has repeatedly alleged the U.S. is hoping to drive him from power.

RACE TO APPOINT A NEW U.N. SECRETARY-GENERAL. Next year the United Nations will choose a new secretary-general. Guterres will finish his second five-year term on December 31, 2026. There is likely to be chatter on the sidelines of the General Assembly next week about who could be a candidate to replace him.

The 15-member U.N. Security Council has to agree on a candidate to recommend to the 193-member General Assembly for election, which means the five council veto powers - Britain, China, France, Russia and the U.S. - have to agree.

(Reporting by Michelle Nichols; Editing by Howard Goller)