China on Tuesday pledged "extreme restraint" in its development of atomic weapons, as world powers met in New York at a key UN conference on curbing the spread of nuclear arms.

"China... exercises extreme restraint over developing nuclear weapons and we will continue to maintain our nuclear power at the lowest level, only for national security needs," foreign ministry spokeswoman Jiang Yu told reporters.

"We are willing to make joint efforts with relevant countries towards nuclear disarmament and a nuclear-weapons-free world," the spokeswoman added.

World powers have gathered at the United Nations for a three-week review conference of the nuclear Non-Proliferation Treaty (NPT), which came into force in 1970 and aims to limit the spread of atomic weapons.

Jiang said China believed the conference, which opened on Monday, would "promote the peaceful use of nuclear energy and international cooperation" on the issue.

But the talks were immediately clouded by a clash between the United States and Iran.

Iranian President Mahmoud Ahmadinejad blasted the United States for threatening to use nuclear arms, triggering a sharp US response and a walkout by several delegations.

Iran is currently the target of UN Security Council sanctions over its disputed nuclear programme, which Tehran insists is solely for civilian energy purposes.

Western powers and Israel believe it is a cover for weapons developments, and are seeking tough new UN sanctions against the Islamic republic.

China, Iran's close ally and a permanent veto-wielding member of the UN Security Council, has repeatedly said diplomacy, not sanctions, is the way to put an end to the Iranian nuclear standoff.

"Dialogue and negotiations are the best way out to resolve this issue and relevant discussions are still under way," Jiang said Tuesday.

"We hope relevant measures can help to properly resolve this issue through dialogue and consultation."

earlier related report
Obama fetes Indonesia on nuclear treaty move
Washington (AFP) May 4, 2010 - US President Barack Obama on Tuesday praised Indonesia for "responsible leadership" after it announced at the United Nations that it would soon ratify the Comprehensive Nuclear Test Ban Treaty (CTBT).

"This is another signal that nations are joining a renewed effort to reinforce global non-proliferation, which advances the vision I outlined in Prague in 2009," Obama said in a written statement.

He said the move, announced at the review conference of the nuclear non-proliferation treaty (NPT) at the United Nations "advances the security of the United States, Indonesia and the world."

"Reinforcing the norm against nuclear testing will help prevent the spread of nuclear weapons and support our efforts to pursue the peace and security of a world without nuclear weapons.

Obama spent several childhood years in Indonesia, and is due to visit the country later this year.

"The United States is committed to the ratification of the Comprehensive Nuclear Test Ban Treaty and to its early entry into force, and we will work with the United States Senate to help achieve advice and consent to this important international agreement," Obama said.

"The United States stands ready to work with all states and encourages them to ratify the treaty and to help bring it into force," said the US president, who has made nuclear non-proliferation and arms reduction a centerpiece of his foreign policy.

Earlier, Indonesian Foreign Minister Marty Natalegawa said his country hoped its decision "will be a positive incentive for other states to follow suit."

Natalegawa said Jakarta was "initiating the process of ratification of the CTBT" in view of recent positive developments with respect to nuclear disarmament and non-proliferation issues.