Mahmoud Ahmadinejad said some saw the 11 September attacks on the US as part of a US conspiracy to protect Israel.

The US denounced his remarks on the 2001 attacks, which killed nearly 3,000 people, as "abhorrent and delusional".

The American delegation was joined in its walk-out by representatives from 32 other nations, including all the EU countries, Canada, Australia, New Zealand and Costa Rica.

But Mr Ahmadinejad appeared undaunted by the protest, continuing his attack on Zionism and Israel.

He said sanctions against Iran are unjust and ineffective, and he stood ready for an annual public dialogue with the US president to air their differences.

The Iranian president said he will host a conference on terrorism next year and that 2011 should be the year of nuclear disarmament.

Repeating Iran's denial that it was seeking the capacity to build nuclear weapons, Mr Ahmadinejad said some members of the UN Security Council has "equated nuclear energy with nuclear bombs".

He also said Tehran will not submit to what he called unnecessary pressure from the the UN nuclear watchdog, the International Atomic Energy Agency.

At the UN General Assembly, leaders take to the stage to make speeches on a subject of their choice.

Iran has already endured four rounds of increasingly punitive economic sanctions over the nuclear dispute.