Washington says its ambassador will boycott meetings of the UN Conference on Disarmament when Iran takes over the rotating chairmanship of the body this month.
The spokeswoman for the U.S. mission to the United Nations, Erin Pelton, said on May 13 in New York that Iran's upcoming rotation as president of the four-week conference beginning May 27 is “unfortunate and highly inappropriate” and "runs counter to the goals and objectives" of the conference itself.
She also said in a statement that a country "in flagrant violation" of UN Security Council and International Atomic Energy Agency obligations should be barred from any formal or ceremonial positions in UN bodies.
The UN Conference on Disarmament is struggling to craft a deal on nuclear disarmament, preventing arms from spreading to outer space, and halting the development of other weapons of mass destruction.
Iran is under UN and other international sanctions for refusing to halt a nuclear-enrichment program that Western nations suspect is aimed at acquiring the ability to produce atomic weapons but that Tehran says is peaceful.
The United States and Europe also accuse Iran of violating a UN embargo of Iranian arms exports to help Syrian President Bashar al-Assad in his attempts to defeat rebels seeking to overthrow him in the country's two-year civil war.
Iran will take over presidency of the Geneva-based disarmament conference from May 27 until June 23 under an alphabetical rotation among its 65 member states.
The conference, launched in 1979 to try to stem the Cold War arms race, is the world's most important disarmament negotiating forum. Although the chairmanship of the body is largely ceremonial, it is a high-profile UN position.
Iran takes over the conference presidency from Indonesia and hands over to Iraq at the end of June.
Based on reporting by Reuters, AFP, and AP