GENEVA - The United States said on Thursday six-power talks with Iran had opened the door to better relations with the West but cautioned Tehran it must take concrete steps to prove it was not seeking nuclear arms.

We've made it clear that we will do our part to engage the Iranian government on the basis of mutual interest and mutual respect but our patience is not unlimited, President Barack Obama said in an address.

Both the United States and Iran said Geneva talks between Tehran and the 'P5+1' powers -- the United States, Britain, France, Germany, Russia and China -- were productive and agreed the contacts would be resumed by the end of the month.

The Iranian government heard a clear and unified message from the international community, Obama said. Iran must demonstrate through concrete steps that it will live up to its responsibilities with respect to its nuclear program.

In what appeared a significant gesture, a senior U.S. official said Iran had agreed 'in principle' to allow its uranium to be sent to Russia for further processing. This would then be returned to Iran in a form suitable for use in a reactor but not of a purity necessary for a bomb.

Tehran also said it would open a newly declared site to U.N. inspectors in the next couple of weeks.

We began good talks in today's negotiations, Tehran's chief nuclear negotiator Saeed Jalili told Iranian media. We have common viewpoints with which we will deal in the continuing talks.

Uncertainty over tensions between Tehran and the West had helped push up crude oil prices slightly on Thursday. Energy markets have kept a close eye on potential disruptions from the OPEC member over recent years due to the protracted standoff.

U.S. Secretary of State Hillary Clinton, speaking in Washington after the talks, said: I think today's meeting opened the door, but let's see what happens.

I think it was a productive day but the proof of that has not yet come to fruition so we will wait and continue to press our point of view and see what Iran decides to do.

The meeting is expected to win Iran a reprieve from further U.N. sanctions, although western powers are likely to be wary of any attempt by Tehran to buy time to develop its nuclear program by holding talks for talks' sake.

The head of the International Atomic Energy Agency (IAEA), Mohamed ElBaradei, will visit Iran this weekend, a senior U.S. official said, speaking on condition of anonymity.

U.S. Undersecretary of State William Burns had met Jalili on the fringes of the P5+1 talks, the highest level contact between the United States and Iran in three decades and emblematic of President Barack Obama's attempts to forge a closer relationship with the Islamic Republic.

Western suspicions that Iran is secretly developing nuclear arms were fueled in the past by Tehran's failure to inform the IAEA of nuclear research installations. Years of nuclear diplomacy have foundered under the weight of mutual suspicion between the West and the Islamic Republic.


Iran declared construction of a second uranium enrichment facility, at Qom last week, deepening Western fears. Uranium refined to a lower level is necessary for nuclear power stations but in higher state of enrichment for bombs.
The West wants Iran to allow immediate U.N. inspections at the plant and give access to documents and employees. Western officials have spoken of the possibility of further sanctions on Iran, perhaps in the oil and gas industry. But diplomats said the question of sanctions was not raised in Geneva.

Iranian Foreign Minister Manouchehr Mottaki said at the United Nations that Iran, which insists its program is designed only for electrical power generation, had now declared all its nuclear facilities.

Time is pressing, French official Jacques Audibert told reporters. There must be proof of a deep evolution in the management of Iran's nuclear program,

EU foreign policy chief Javier Solana said Iran had promised to cooperate fully and immediately with the IAEA on the new enrichment facility near Qom.

(It) will invite them soon, within the next couple of weeks, he told reporters.

Iranian nuclear chief Ali Akbar Salehi said the gates of the Qom site were open in principle but protocols had to be observed. Inspections will take place is not far away.

The Russian state-controlled RIA agency quoted a source close to the talks as saying Moscow was ready to discuss enriching Iranian uranium from 4 percent purity to 19.75 percent suitable for civilian reactors if, of course, such a request comes from the IAEA.

A U.S. official said an Iranian agreement in principle to ship most of its uranium overseas could be significant.

It will remove that source of anxiety, the official said.

A White House spokesman appeared to allude to the possibility of sanctions, should further talks prove fruitless.

If at any point this appears to simply be the Iranians trying to talk some issue to death, then I think working in concert with, and common purpose with our P5+1 partners, we'll take additional steps to ensure that Iran knows we mean business, he said.

(Additional reporting by Parisa Hafezi and Stephanie Nebehay in Geneva, Steve Holland in Washington, Fredrik Dahl in Tehran and Jonathan Saul in London; writing by Ralph Boulton; editing by Myra MacDonald)