Iran's nuclear ambitions are putting the world at risk, US Secretary of State Hillary Clinton has warned.

美国国务亲希拉里·克林顿警告道，伊朗的核武器野心将使世界处于危险之中。

She told delegates（代表） at a nuclear Non-Proliferation Treaty (NPT不扩散核武器条约) conference that Iran had violated its obligations and should be held to account.

Earlier, President Mahmoud Ahmadinejad of Iran accused states with nuclear weapons of threatening those who wanted to develop peaceful nuclear technology.

His comments prompted delegates from the US, the UK, France to walk out.

The US Department of Defense¹ later disclosed（揭露，公开） that it had a total of 5,113 nuclear warheads in its arsenal²（军械库） , a closely-guarded secret for decades.

Mrs Clinton said the move was to improve transparency in the nuclear disarmament（裁军） regime and encourage other nations to comply with it.

"So for those who doubt that the United States will do its part on disarmament, this is our record, these are our commitments and they send a clear unmistakable signal," she told the NPT conference.

'Fire against humanity'

Throughout her speech on Monday, Mrs Clinton regularly rounded on（斥骂） Iran, accusing President Ahmadinejad of offering the same "tired, false and sometimes wild accusations⁴" against the US and others.

"Iran will do whatever it can to divert attention away from its own record in an attempt to evade⁵（逃避） accountability," she said.

"Iran is the only country represented in this hall that has been found by the [International Atomic Energy Agency] board of governors to be currently in non-compliance with its nuclear safeguard obligations."

"It has defied the UN Security Council and the IAEA and placed the future of the non-proliferation regime in jeopardy⁶（危险） , and that is why it is facing increasing isolation⁷ and pressure from the international community," she added.

The US is currently negotiating with other Security Council members to impose a fourth round of UN economic sanctions against Iran over its uranium enrichment programme.

Tehran insists its nuclear programme is entirely⁸ peaceful.

The Nuclear Non-Proliferation Treaty (NPT) comprises a grand bargain, BBC Diplomatic correspondent Jonathan Marcus says.

The five major nuclear powers - the US, the former Soviet⁹ Union, China, the UK and France - agreed to eventually disarm³. Other signatories agreed never to develop nuclear weapons in return for receiving full access to civilian¹⁰ nuclear technology.