The delegations of the U.S., Britain and France walked out of the UN General Assembly Hall in New York where a review conference on nuclear non-proliferation is under way after Iranian President Mahmoud Ahmadinejad accused Western powers of double standards concerning nuclear non-proliferation.

Addressing the delegates from 189 nations, Ahmadinejad said representatives of the countries that "threaten to use nuclear weapons against non-nuclear-weapon states" should be excluded from International Atomic Energy Agency's governing bodies.

The U.S., he said, was the only country to use nuclear weapons, pointing to the 1945 bombing of Hiroshima and Nagasaki. He also said that Wahington had never fulfilled its obligations concerning nuclear non-proliferation.

The Iranian leader urged the U.S. to withdraw its nuclear weapons from European and Asian non-nuclear-weapon countries - Italy, Germany, Britain, Netherlands and Japan.

The U.S., as well as Israel, has not ruled out a military action against Iran in case Tehran fails to meet a demand by Western powers and halt its controversial nuclear program. The Islamic Republic is accused of developing nuclear weapons under the guise of a civilian nuclear energy generation.

Answering a call by UN Secretary General Ban Ki-moon, who said the Islamic Republic should agree to the UN plan stipulating the exchange of Iran's low-enriched uranium for nuclear fuel produced abroad, Ahmadinejad said Iran was never opposed to this plan.

"Iran was always ready for this, and I want to announce once again that it is acceptable for Iran, and we have made our proposal concerning the issue," he said, adding "now, the ball is on the side of other states, which should accept our proposals."

In line with the UN plan drawn up in Vienna last October, the Islamic Republic was to ship out its low-enriched uranium to Russia for further enrichment and subsequently send it to France where it would be made into fuel rods.

Tehran stalled the plan, suggesting it could consider a simultaneous swap of its low-enriched uranium for 20%-enriched uranium, but that the exchange should be simultaneous and would have to take place on its own territory.

IAEA chief Yukiya Amano said at the conference that the agency was unable to confirm the peaceful nature of Iran's nuclear program as the Islamic Republic was not cooperating with the IAEA properly.

The six mediators on Iran's nuclear program - Russia, China, the U.S., Britain, Germany and France - have begun discussing the text of a draft resolution imposing new sanctions on the Islamic Republic.

The Nuclear Non-Proliferation Treaty Review Conference will run in New York until May 28. The participants in the conference are expected to issue a joint declaration summing up the results of the talks.