The 11th conference to review implementation of the NPT, which came into force in 1970, began on Monday at the United Nations in New York.

Different groups nominated 34 conference vice ​presidents, and the conference chair, Vietnam’s UN ambassador Do Hung Viet, said Iran was picked by “the ​group of non-aligned and other states.”

Christopher Yeaw, assistant secretary for the US Bureau of ⁠Arms Control and Nonproliferation, told the conference that Iran’s selection was an “affront” to the NPT.

He claimed it ​was “indisputable that Iran has long demonstrated its contempt for the non-proliferation commitments of the NPT,” and had refused ​to cooperate with the UN nuclear watchdog to resolve questions about its programme.

He called Iran’s selection “beyond shameful and an embarrassment to the credibility of this conference.”

Reza Najafi, who serves as Tehran’s ambassador to the International Atomic Energy Agency, rejected the US ​statement as “baseless and politically motivated.”

“It is indefensible that the United States, as the only state ever to have ​used nuclear weapons, and the one that continues to expand and modernise its nuclear arsenal… seeks to position itself as ‌an arbitrator ⁠of the compliance,” he told the meeting.

The nuclear issue has been at the heart of the two-month war between Iran and the United States and Israel, with US President Donald Trump reiterating on Sunday that Iran can never have a nuclear weapon.

Iran has long demanded Washington acknowledge its right to enrich uranium, which Tehran says it only ​seeks for peaceful purposes, ​but which Western powers ⁠say could be used to make nuclear weapons.

Iran has insisted it does not seek nuclear weapons. But the IAEA and the US intelligence community separately assessed that ​Tehran had a nuclear weapons development program that it shuttered in 2003.

On Monday, ​Iranian sources disclosed ⁠Tehran’s latest proposal to end the conflict, which would set aside discussion of Tehran’s nuclear programme until the war is ended and disputes over shipping from the Gulf are resolved.

Trump and his top national security aides met to ⁠discuss the ​conflict on Monday, and White House spokeswoman Karoline Leavitt told ​reporters “the president’s red lines with respect to Iran have been made very, very clear, not just to the American public, but also to ​them as well.”