Iran’s top nuclear negotiator Ali Larijani and EU foreign policy chief Javier Solana were due to meet on Thursday, possibly in Spain, for their second encounter in just over a month.

‘For the Larijani-Solana meeting, no date or venue has been set,’ Iranian foreign ministry spokesman Mohammad Ali Hosseini told reporters. ‘With the agreement of both sides it has been postponed.’

He said that the delay had been agreed in a telephone conversation between the two men and was required as both sides needed more time to study their options for the talks.

‘There was a meeting at the level of experts. There was an exchange of views and plans. But some of these plans need greater evaluation and study.’

Hosseini did not give further details on the reasons for the delay or say where and when the meeting of experts took place. There was no immediate confirmation of his announcement from Brussels.

The meetings between Larijani and Solana are central to diplomatic efforts to resolve the standoff, which has already seen Iran slapped with two sets of UN sanctions for its refusal to suspend uranium enrichment.

After missing the latest UN Security Council deadline to suspend the process, Western powers are now pressing for Iran to face further penalties for its defiance.

Even when the pair actually meet, it remains unclear whether the two sides will be able to achieve any breakthrough, with the EU wanting Iran to freeze uranium enrichment and Teheran refusing to even consider such a move.

Iran’s right to enrichment is the main obstacle toward resolving the standoff as the sensitive process can be used both to make nuclear fuel and highly enriched uranium for the explosive core of an atomic bomb.

The United States accuses Iran of seeking nuclear weapons, a charge vehemently denied by Teheran which says it just wants to produce energy for a growing population whose fossil fuels will eventually run out.

Washington has never ruled out the use of force to resolve the standoff and has sent a clear warning to Iran by sailing two nuclear-powered aircraft carriers through the Straits of Hormuz.

Hosseini however brushed off the move. ‘The US military build-up in the Persian Gulf is aimed mostly at lifting their spirits,’ he commented.

The announcement of the postponement also comes amid protests from Western powers over comments by UN nuclear watchdog chief Mohamed ElBaradei that they should change their stance towards Iran’s nuclear drive.

ElBaradei has said in a series of recent interviews that the international community should deal realistically with the fact that Iran has attained the know-how to enrich uranium and should allow it to conduct some enrichment.

The Larijani-Solana talks were also due to have come just three days after eagerly awaited talks in Baghdad on Monday between Iran and its arch enemy the United States.

The talks between US ambassador to Iraq Ryan Crocker and Iranian ambassador Hassan Kazemi are to be highest-level official bilateral talks between the two sides since the 1979 Islamic revolution.