GENEVA - Talks between Iran and six major powers over Tehran's nuclear program on Thursday opened the door to improved relations as Iran agreed to allow U.N. inspectors into a newly disclosed uranium enrichment plant.

Both the United States and Iran described the talks between Tehran and the six powers -- Britain, France, Germany, Russia and China as well as the United States -- as productive and agreed the contacts would be resumed by the end of the month.

In Washington, President Barack Obama described the meeting in Geneva as a constructive beginning but insisted that Iran must demonstrate to the United States and its European allies that it was not seeking nuclear weapons. Iran insists its nuclear program is designed only for electrical power generation,

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

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.

The conciliatory tone of the discussions, which included the highest-level direct talks in three decades between Iranian and U.S. officials, appeared to ease some of the tension between Tehran and the United States and its European allies, which have been threatening Iran with stringent new sanctions.

Oil prices rose in afternoon activity due to the tensions, before easing in late trade after Obama spoke. Concerns the standoff could lead to a supply disruption have supported prices at various times in recent years.

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.

In what appeared to be 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. It 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 throw open a uranium enrichment plant near the holy city of Qom to U.N. inspectors in the next couple of weeks. The underground nuclear fuel facility had been kept secret until Iran disclosed its existence last week, setting off an international furor.


Underlining the determination of the big powers to move ahead with a rapid U.N. inspection of the plant, Obama insisted Iran must meet its pledge.

It must grant unfettered access to IAEA inspectors within two weeks, he said referring to the U.N. nuclear watchdog.

The International Atomic Energy Agency head, Mohamed ElBaradei, will visit Iran this weekend, a senior U.S. official said.

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 soon ... it is not far away, he said.

EU foreign policy chief Javier Solana said Iran had promised to cooperate fully and immediately with the IAEA on the Qom facility. (It) will invite them soon, within the next couple of weeks, he told reporters.
Thursday's talks are expected to win Iran a reprieve from tougher 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.

U.S. Secretary of State Hillary Clinton said after the talks, 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.

U.S. Undersecretary of State William Burns met Jalili for about 45 minutes on the fringes of the main talks, the highest- level contact between the United States and Iran in three decades and emblematic of Obama's attempts to forge a closer relationship with the Islamic Republic.

At the United Nations, Iranian Foreign Minister Manouchehr Mottaki said Iran 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.

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.

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.

(Additional reporting by Stephanie Nebehay in Geneva, Steve Holland in Washington, Fredrik Dahl in Tehran and Jonathan Saul in London; Writing by Chris Wilson; Editing by Peter Cooney)