World leaders have much to discuss when the assembly begins [Reuters]

A global financial crisis remains high on the agenda, many member nations are at odds with each other and there are increasingly strident calls for reform of the UN itself.

The assembly is the only one of five main UN bodies where all 192 member nations of the organisation are equally represented, and all will get their chance to address those gathered and, as one observer put it, to "eyeball" their global counterparts.

A plethora of powerful - and controversial - political heavyweights are also to address the assembly in the coming days, including George Bush, the US president, Mikheil Saakashvili, the Georgian leader and Mahmoud Ahmadinejad, the Iranian president.

In addition to official events, scores of meetings will be held on the sidelines on everything from the Middle East conflict to the Iranian nuclear crisis.

In anticipation of scores of world leaders descending on the area, New York has braced itself for the inevitable traffic snarls, with scores of barricades around the UN's headquarters, concrete road blocks and police on every corner.

But it will be inside the UN building that tensions may erupt.

Soured relations

Protesters gathered to urge the UN to take action against Iran

The ongoing tensions with Russia over Georgia, which exploded in August, exposed how swiftly relations between Russia and the US has soured and to many raised the bleak prospect of a new "Cold War".

Ahmadinejad will also address the assembly on Tuesday, only a few days after the UN's nuclear watchdog, the International Atomic Energy Agency warned it had still not been able to resolve crucial questions over the nation’s nuclear programme.

Protests

On Monday, a crowd of protesters from various US Jewish groups angered by Iran's presence at the UN assembly made their presence felt a short distance from the UN headquarters, many expressing anger that Ahmadinejad is being permitted to even speak.

Rabbi Jonathan Pearl, of New York, who attended the protest, told Al Jazeera the world "owes itself the opportunity to stop evil while we still can".

"[Ahmadinejad] is a madman threatening and promising to carry out the annihilation of a member state of the UN. How can this body host someone who threatens a nation state? That's illegal according to the UN charter," he said.

Meanwhile Venezuela's foreign minister is also due to speak on Tuesday, along with Alvaro Uribe, president of Colombia, in a year when the region veered dangerously close to all out war over Colombia’s controversial deadly cross-border raid into Ecuador.

All will be keen to put their message across, and the US may well be listening.

The assembly debate comes only a few weeks before the US holds its presidential election, and days before the first presidential debate between Barack Obama, the Democratic candidate, and John McCain, his Republican rival, on foreign policy.

In addition, Sarah Palin, McCain's controversial running-mate, is due to meet Hamid Karzai, the Afghan president, and Uribe, on the sidelines of the assembly in a bid to bolster her foreign policy credentials.

Reform calls

While the US prepares to change its leadership, the US has also been one of the most vocal nations in calling for change within the UN.

Miguel D'Escoto Brockmann, a priest and former Nicaraguan foreign minister and the assembly's new president, urged the assembly last week to prepare for "democratisation".

And he did not mince his words when it came to criticism of some member states, accusing some of an "addiction to war", criticising the UN Security Council as having their veto power going to their heads, and saying the UN’s biggest mistake had been its failure to establish a Palestinian state.

His strident comments led to admonishments from the US and Israel but pointed to one of the key conundrums at the heart of the UN's assembly and the UN itself –  whether it is a fundamentally sound institution in need of reorganisation, or whether it needs to be completely rebuilt from the bottom up.

Linda Jamison, senior fellow for the Centre for Strategic Studies and former head of the UN office for project services in Washington DC, says reform is "an enormous task" and cites three main issues – with reform of the UN's security council a top priority".

The security council is viewed by many, Jamison argues, as a "Cold War" entity that is largely dysfunctional and unrepresentative of the modern political landscape.

In addition, she says, the UN must work on "improving the organisation’s operational capacity and also its oversight functions. All three need to be in tip top shape for the UN to serve its mandates".

"The general assembly must be vigilant in its processes and mandates and in how it goes forward in political environments that are constantly shifting. It also needs to be better at mobilising its resources for international events," she says.

Such reform starts in many ways, she says, from the top down, with Ban Ki-moon, the secretary-general, facing enormous challenges.

"We've had stewardship [in the past] and we need leadership," she says.

Weighty challenges

The UN is also facing further calls for action over rising food prices, which led to food riots in dozens of countries this year.

On Monday, Ban called on the world's richest nations to spend $72bn a year to help Africa achieve the UN's goals of fighting poverty, improve health and ensure universal primary education, despite the current global credit crunch.

It will also be meeting to discuss the organisation's ambitious – some say unrealistic -  Millennium Development goals, which aim to cut global poverty in half by 2012.

The current global financial crisis will also dominate proceedings, something Ban acknowledged last week when he said the world was experiencing a "development emergency".

"This week, with the help of all world leaders, I would like to really mobilise necessary resources and galvanise political will as high as possible as I can," he said.