US President Barack Obama said an announcement of six-power talks with Iran offered a diplomatic chance to defuse a crisis over its nuclear program and quiet the "drums of war".

European Union foreign policy chief Catherine Ashton, who represents the United States, Russia, China, France, Britain and Germany in dealings with Iran, announced on Tuesday a fresh bid to allay suspicions that Iran is developing nuclear weapons after weeks of consultations with the other powers.

A date and venue have yet to be agreed for the talks, proposed by Iran after a year of diplomatic standstill that has increased fears of a slide into a new Middle East war.

Amid mounting speculation that Iran's nuclear sites could be attacked in coming months, Obama said that American politicians "beating the drums of war" had a responsibility to explain the costs and benefits of military action. He said the notion that the United States needed to make a choice in the coming weeks or months was "not borne out by facts".

But he said Washington would "not countenance" Iran getting a nuclear weapon, shortly after Defense Secretary Leon Panetta said the United States would take military action to prevent this from happening if diplomacy failed. "Military action is the last alternative when all else fails," Panetta told the annual policy conference of the biggest US pro-Israel lobbying group, AIPAC. "But make no mistake, when all else fails, we will act."

With Israel speaking increasingly loudly of resorting to military action, the talks could provide some respite in a crisis that has driven up oil prices and threatened to suck the United States into its third major war in a decade. Iran's nuclear negotiator, Saeed Jalili, wrote to Ashton in February saying Teheran wanted to reopen negotiations and offered to bring unspecified "new initiatives" to the table.

"Today I have replied to Dr Jalili's letter of Feb. 14," Ashton, speaking on behalf of the six powers after weeks of consultations with them, said in a statement. "I have offered to resume talks with Iran on the nuclear issue."

A senior EU official said these talks were not expected before the Iranian New Year in two weeks, though there would be a series of preparatory meetings, possibly in the coming days.

"Our overall goal remains a comprehensive, negotiated, long-term solution which restores international confidence in the exclusively peaceful nature of Iran's nuclear program, while respecting Iran's right to the peaceful use of nuclear energy," Ashton said in her reply to Jalili.

Western states are likely to tread cautiously, mindful of past accusations that Iran's willingness to talk has been a stalling tactic to blunt pressure and not a route to agreement.

The Islamic Republic's latest approach to the six powers comes at a time when it is suffering unprecedented economic pain from expanding oil and financial sanctions.

China's response

China welcomes the positive progress made by the international community in resolving Iran's nuclear issue, Foreign Ministry Spokesman Liu Weimin said on Wednesday on a regular press conference.

Liu made the remarks while commenting on Ashton's recent letter to Iran accepting its offer to resume talks.

Liu said France, Britain, Germany, China, Russia and the United States recently reached a consensus with Iran on resuming the talks.China has been working on a peaceful solution to the Iranian nuclear issue through dialogue, and has made positive efforts to push for the resumption of the talks, Liu said.

Reuters-China Daily