The United States and key allies urged actions as well as words in a wary response Wednesday to Iran's surprise U-turn on proposals to swap enriched uranium for nuclear fuel.

And there was alarm as Iranian President Mahmoud Ahmadinejad's apparent overture to the West on the nuclear issue was smartly followed by a rocket launch into space deemed by the White House "a provocative act."

Ahmadinejad bamboozled his critics on Tuesday by suggesting that a deal struck last October envisaging Iran would send some 70 percent of its low-enriched uranium abroad was suddenly back on.

Conscious his remarks could simply to be timed to stave off new sanctions at an upcoming meeting of world powers, the White House urged Iran to contact the International Atomic Energy Agency (IAEA), the UN watchdog that brokered the original deal.

"If those comments indicate some sort of change in position for Iran, then president Ahmadinejad should let the IAEA know," said deputy White House spokesman Bill Burton.

Iran needs nuclear fuel to power its UN-monitored reactor, but the West fears its uranium enrichment program is masking efforts to produce atomic weapons -- claims vehemently denied by the Islamic republic.

The IAEA has proposed, in a bid to allay Western fears about Iran's atomic ambitions, that Tehran ship out its low-enriched uranium (LEU) to Russia and France to be further purified into reactor fuel.

Iran, which agreed in principle to the offer during talks with world powers in Geneva in October, later appeared to reject the deal and said it preferred a gradual swap of LEU with fuel -- preferably on Iranian soil.

It had given the West until January 31 to respond to its counter-proposals.

Iran's apparent change of heart received a cautious welcome from the P5+1 -- UN Security Council veto-wielding permanent members Britain, China, France, Russia and the United States plus Germany -- which has been leading international efforts to engage Iran.

Britain's Foreign Office said: "If Iran is willing to take up the IAEA's proposed offer, it would be a positive sign of their willingness to engage with the international community on nuclear issues."

But it said that desire must be made "clear" to the IAEA and Ahmadinejad's comment "does not change" the need for Iran to hold talks with the P5+1.

"Iran has to make concrete commitments to the IAEA and a concrete answer in Vienna is the only measure on which it can be assessed," German government spokesman Ulrich Wilhelm said.

And French Prime Minister Francois Fillon said he would ask the United Nations to adopt a new resolution against Iran, warning it would include "strong sanctions".

"The Iranian regime has not taken our offers of dialogue ... the time has therefore come to react," he said.

But hours after Ahmadinejad said on state television that Iran would have "no problem" sending its stocks of low-enriched uranium abroad, the launch of a new Iranian space rocket drew fresh international criticism.

"This announcement can only reinforce the concerns of the international community as Iran in parallel develops a nuclear program that has no identifiable civil aims," a French foreign ministry spokesman said.

The launch Wednesday of the Kavoshgar 3 (Explorer) rocket -- a home-built satellite carrying a rat, turtles and worms -- was Iran's first experiment with such space technology.

The West suspects Iran of secretly trying to build an atomic bomb and fears the technology used to launch space rockets could be diverted into developing long-range ballistic missiles capable of carrying nuclear warheads.

Iran strongly denies that either its space or atomic energy programs are intended to build a bomb.

The United States said Tuesday it hoped to consult with China and the other P5+1 powers in the coming days on the Iranian nuclear issue, but gave no precise date for a meeting.

If Ahmadinejad was simply paying lip-service to a deal to try and avoid stiffer sanctions then the move didn't appear to have worked.

US Defense Secretary Robert Gates issued an unusually stern warning Wednesday that Iran faced the prospect of "severe sanctions" if it failed to answer Western concerns.

earlier related report
EU foreign chief calls for prudence on Iran sanctions
Brussels (AFP) Feb 3, 2010 - EU foreign policy chief Catherine Ashton has cautioned against any hasty European move to slap new sanctions on Iran over its nuclear programme, also announcing she is assuming the role of international intermediary on the issue.

In an interview with AFP, Ashton distanced herself from the position of EU nations, such as France, that are pushing for extra sanctions on Tehran which the West suspects of seeking to develop nuclear arms under cover of a civil energy programme.

"We're not moving quickly on anything," she said, emphasising the need for a UN Security Council decision.

Western nations who suspect Iran of seeking a nuclear bomb on Wednesday called on the Islamic state to make a firm commitment to the UN atomic watchdog to have its uranium fuel enriched abroad.

Iran appeared to carry out a policy U-turn when President Mahmoud Ahmadinejad said Tuesday that Iran would have "no problem" sending stocks of low-enriched uranium to other countries to be refined into reactor fuel.

The United States and its European allies were surprised by the comment after Iran had earlier rejected a deal drawn up by the International Atomic Energy Agency (IAEA) in a bid to ease growing tensions.

The UN Security Council has already passed three rounds of sanctions against Iran over its nuclear programme. Ashton said the ball remained in the UN's court.

"What we're doing is we're saying very clearly that the next step on Iran is through the Security Council. I'm very clear on that," said the EU's High Representative for Foreign Affairs and Security Policy, a new post created by the EU's reforming Lisbon Treaty.

Paris has urged its European Union partners to prepare new sanctions against Iran, saying they were now required due to Tehran's intransigence over its nuclear programme.

France is "concerned" by Iran's announcement that it has launched a home-built rocket because the technology behind it could also be used to fire ballistic missiles, the foreign ministry said.

"This announcement can only reinforce the concerns of the international community as Iran in parallel develops a nuclear programme that has no identifiable civil aims," a spokesman said.

Iran hailed on Wednesday the successful launch of a home-built satellite carrying a rat, turtles and worms. Tehran however denies having military goals for its space programme or its nuclear drive.

Ashton said meanwhile she was assuming the role of chief international nuclear negotiator with Tehran, a post occupied until the end of last year by the then EU foreign policy chief Javier Solana -- whose role has been subsumed into her expanded office.

"I take over Javier's position," she said of the post of representative of the six world powers involved in the talks -- Britain, China, France, Germany, Russia and the United States.

"One of the things I've been doing is looking back over the six years of dialogue that Javier has had with Iran. I still want to see dialogue," the British peer added, without giving a date for any future talks.

"It's very important to find a solution through talking but unfortunately we're in a position where we also have to look at what else needs to happen, hence the Security Council," Ashton said.

The EU foreign affairs chief also said she would make her first official trip to the Middle East next month, hoping to relaunch peace talks between the Israelis and the Palestinians.