Western powers expressed scepticism over the deal Iran agreed with Brazil and Turkey on Monday to send some of its uranium abroad, reviving a fuel swap plan drafted by the UN earlier.

The White House said Iran must take steps to prove its nuclear programme was for exclusively peaceful purposes. 'Given Iran's repeated failure to live up to its own commitments ... the United States and international community continue to have serious concerns,' a spokesman said.   

'I think we are making steady progress on a sanctions resolution.'    

A State Department spokesman said the United States would 'engage Iran anywhere, anytime, provided Iran is prepared to address the international community's concerns about its nuclear program', but would continue to pursue new sanctions.   

Turkish Foreign Minister Ahmet Davutoglu called the fuel swap deal a 'historic turning point'.

'My expectation is that after this declaration there will not be a need for sanctions,' Turkish Prime Minister Tayyip Erdogan said, echoing a statement by Brazil.   

The International Atomic Energy Agency (IAEA), which would oversee the nuclear material under the plan, said it had seen the declaration and was waiting for Iran to agree to the 'relevant provisions' in writing.

Britain said work on a new UN sanctions resolution must go on. Iran's move 'may just be a delaying tactic', said Foreign Secretary William Hague.

France said the deal would not resolve core concerns. 'Let us not deceive ourselves, a solution to the (fuel) question, if it happens, would do nothing to settle the problem posed by the Iranian nuclear programme,' French Foreign Ministry spokesman Bernard Valero said in a statement.

Russian President Dmitry Medvedev expressed similar concern. 'One question is: will Iran itself enrich uranium? As far as I understand from officials of that state, such work will be continued. In this case ... those concerns that the international community had before could remain,' Medvedev said.

Medvedev spoke by phone to Brazilian President Luiz Inacio Lula da Silva later and 'positively assessed joint efforts by Brazil and Turkey to promote a political and diplomatic solution to the Iranian nuclear problem', a Krelin statement said.

'After this, we need to decide what to do: Are those proposals sufficient or is something else needed? So I think a small pause on this problem would not do any harm,' he said.

Washington has been leading a push to impose new sanctions, and especially to win the backing of permanent UN Security Council members Russia and China.

Analysts say Monday's agreement may allow Tehran to stave off a fourth round of sanctions and help the leadership reassert its authority after months of anti-government unrest that followed a disputed presidential election last June.

Despite the deal, Iran made clear it had no intention of suspending domestic enrichment the West suspects is aimed at making bombs.

'There is no relation between the swap deal and our enrichment activities,' Ali Akbar Salehi, head of Iran's Atomic Energy Organisation, told Reuters.

He told Iranian television the deal was a move towards nuclear cooperation and 'stopping sanctions'.   

Iran launched work to enrich uranium to a 20 percent level in February. Further enrichment would be needed to make weapons.   

A European Commission spokesman said the deal might be a step in the right direction, but details needed to be seen.

Lula, Erdogan and Iranian President Mahmoud Ahmadinejad clinched the agreement after hours of talks in Tehran, Iranian state media reported. Turkey and Brazil are both non-permanent members of the UN Security Council.

Iran said it had agreed to transfer 1,200 kg (2,646 lb) of its low-enriched uranium (LEU) to Turkey within a month and in return receive, within a year, 120 kg of 20 percent-enriched uranium for use in a medical research reactor.   

Iran, which says its atomic programme is purely for peaceful purposes, had earlier insisted any such transfers must take place simultaneously and on its territory.

'Iran expressed its readiness to deposit its LEU within one month. On the basis of the same agreement the Vienna Group should deliver 120 kg fuel required for Tehran research reactor in no later than one year,' a joint declaration said.

Iranian Foreign Ministry spokesman Ramin Mehmanparast said Iran's LEU would be under the supervision of the Vienna-based IAEA in Turkey. The IAEA would be notified within a week about the swap deal, he said. - Reuters