United Nations: US President Barack Obama on Thursday echoed a call from Iran's leader for new negotiations to end the standoff over Tehran's nuclear program, but each side showed wariness of the other's intentions.

Under the world spotlight in New York, Obama told the UN General Assembly that the door to diplomacy with Iran remains open, four months after Washington obtained harsh new UN sanctions against Tehran.

But Obama said the Islamic Republic must show a credible commitment to dialogue on its nuclear program, which Washington fears masks a drive to build a nuclear weapon. Iran insists its aims are only peaceful.

His speech came as Iranian President Mahmud Ahmadinejad, who was due to address the assembly shortly, argues it is Tehran, not the West, that is serious about reviving talks that lapsed as soon as they began last year.

"Our position is clear: when I say that we will talk, we will talk. We are not afraid of holding a talk," the Iranian leader told a group of foreign policy experts here Wednesday night.

But he said Western nations had not been responsive.

Obama reaffirmed his willingness to resume talks, which have been interrupted for months.

"Let me be clear once more: the United States and the international community seek a resolution to our differences with Iran, and the door remains open to diplomacy should Iran choose to walk through it," he told the UN.

"But the Iranian government must demonstrate a clear and credible commitment, and confirm to the world the peaceful intent of its nuclear program," he said in a speech touching on a range of foreign policy issues.

Following a meeting here Wednesday, US Secretary of State Hillary Clinton and her counterparts from Britain, China, France, Germany and Russia called for an "early negotiated settlement" to the Iranian nuclear issue.

US officials confirmed that there had been signs from the Iranians that they might be ready for a meeting in the fall.

A joint statement said the six powers were "ready to engage with Iran" in the context of implementing a deal agreed in Geneva in October last year under which Iran would give up enriched uranium in exchange for nuclear fuel.

It added that they looked forward to an "early meeting" with Iran and were prepared to discuss a "revised arrangement," apparently because Iran has enriched much more uranium since the earlier offer was made.

Under the deal, Iran would ship most of its low-grade uranium to France and Russia so that it could be enriched further and returned to Iran to fuel a medical research reactor in Tehran.

The deal had been designed to buy time and build confidence while the world community presses Iran to meet its demand to halt uranium enrichment. But the deal stalled as Iran sought to modify its terms.

In June, the UN Security Council then approved a fourth round of sanctions against the Islamic republic, which in turn said it would suspend talks until September.

The United States, which spearheaded the drive for the sanctions, has long argued that Iran will only return to the negotiating table once it feels them bite.

Iran has denied US contentions that the Islamic republic is starting to feel the pinch.

Speaking at a New York hotel on Wednesday night, Ahmadinejad said Iran's nuclear negotiator Saeed Jalili had for months contacted Catherine Ashton, the EU foreign policy chief and lead for contacts with Iran, to set a date for talks.

"Each time she kept postponing the talks," Ahmadinejad said, reiterating his willingness to resume talks.

"We say what we think but we don't know who the other side is - we don't know who is deciding on the other side," Ahmadinejad said.

Meanwhile, German Foreign Minister Guido Westerwelle hailed Obama's remarks on Iran.

"We welcome very favorably the fact that the offer of dialogue with Iran remains valid," he said, adding it was a forward-looking position and hoping it would spark new momentum.

"The situation is extraordinarily difficult but it's the only chance also for Iran to not suffer the sanctions," he said.