"Ali Larijani and Javier Solana will meet and talk on May 31 in Madrid," a source in Iran's supreme national security council told the state-run IRNA agency.

Solana had earlier confirmed at the eighth Asia-Europe meeting (ASEM) in Hamburg that he will hold talks on Thursday in the Spanish capital with Larijani, the head of Iran's national security council.

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.

The Madrid talks will be their second encounter in just over a month after a previous meeting in Ankara. Larijani and Solana are seeking to see if there is scope for opening full negotiations to break the deadlock.

But it remains unclear whether the two sides will be able to achieve any breakthrough, with the EU wanting Iran to freeze uranium enrichment and Tehran refusing to even consider such a move.

The talks in Ankara from 25-26 April were "positive in form but not fruitful in substance," Solana's spokeswoman Cristina Gallach said in Brussels.

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, in highly extended form, to produce the fissile core of an atomic bomb.

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.

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

There had been confusion on Sunday as to whether the latest Larijani-Solana meeting would go ahead after the Iranian foreign ministry said it was postponed by mutual agreement but then confirmed it was on schedule.

The meeting will come just three days after the ground-breaking talks in Baghdad on Monday between Iran and its arch-enemy the United States.

The talks between the US ambassador to Iraq Ryan Crocker and his Iranian counterpart Hassan Kazemi Qomi were the first time in 27 years that such high ranking officials have sat down together to discuss a bilateral issue.

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.

Gallach said that the US-Iran talks on Thursday, which were limited to discussing the security chaos in Iraq, "could only be positive".

Solana and Larijani aides also met discreetly in Brussels on Friday to prepare for the fresh talks, she added.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.