UNITED NATIONS: US President Barack Obama and Iran`s leader Mahmoud Ahmadinejad take their political rivalry to the UN General Assembly on Thursday when world leaders start their annual debate.

The Middle East, the possible breakup of Sudan, the Iran and North Korean nuclear programmes, climate change and UN reform are likely to dominate speeches.

Obama and Ahmadinejad will appear on the assembly podium a few hours apart on the first day of the 65th UN General Assembly.

Obama outlined a new US development aid policy at a UN summit on the fight against poverty that ended Wednesday.

He must now turn his attention to foreign policy, with the West`s accusations that Iran is trying to develop a nuclear bomb near the top of the agenda.

Ahmadinejad, who denies his country is seeking a bomb, warned in New York this week that Iran would take it as an act of war if a US-backed Israeli strike on Iranian nuclear facilities is carried out.

The Iranian president is accompanied by major security on each of his outings into New York during his annual stay for the UN assembly.

About 140 heads of state and government are in New York this week for the UN poverty summit and the General Assembly. About 35 of them will speak on Thursday, with Chinese Premier Wen Jiabao also on the schedule.

UN Secretary General Ban Ki-moon will start the assembly with a speech entitled "Pulling Together In Testing Times".

On the sidelines of the assembly several, Ban will host several leaders at a special meeting on peacekeeping and peacebuilding.

On Friday, Obama will attend a special meeting on Sudan. Troubled preparations for two self-determination votes in January have led to heightened international worries that South Sudan could unilaterally declare independence.

BDST: 10:08 HRS, September 23, 2010