Larijani struck an upbeat note in an interview with Spain's El Pais newspaper which he gave after talks with European Union foreign policy chief Javier Solana, saying the impasse could be resolved.

"We discussed concepts which can serve as the base for negotiations and we have put forth ideas to unblock the current situation," he told the paper.

"We have agreed to work on this in the coming two weeks. This indicates that the capacity to resolve the issue exists. I don't want to exaggerate but the potential is there."

Larijani also said if the United States, which accuses Iran of seeking to develop nuclear weapons, halted its "doctrine of unilateralism, militarism and preventive attacks... it could serve as a basis to resolve contentious issues."

Tehran vehemently denies Washington's accusation, saying it wants only to generate energy for a growing population when fossil fuels eventually run out.

Solana's spokesman also echoed Larijani after Thursday's talks, saying there had been "some progress on a series of questions."

However UN Secretary General Ban Ki-moon on Sunday said he was "disappointed" that the talks had failed to produce any concrete results.

"I have been disappointed that there have not been any concrete results during the negotiations between Iran and the EU," he told Spain's ABC daily in an interview.

"I sincerely hope that the Iranian authorities will continue to be involved in negotiations with the international community, especially with the European Union," he said.

Meanwhile, Tehran on Sunday defiantly dismissed US threats of further United Nations sanctions, vowing to press ahead with its controversial atomic drive and with enriching uranium.

"Sanctions cannot dissuade us and will not have any effect," foreign ministry spokesman Mohammad Ali Hosseini told reporters in Tehran.

Hosseini stressed that Iran was not offering any concession on the EU's key demand that Tehran suspend uranium enrichment, a process that can be used to make nuclear fuel but also the explosive core of an atomic bomb.

US officials expressed frustration after the talks, saying there was no sign of Iran offering any suspension and the only option was for the UN Security Council to discuss a third set of sanctions against Tehran.

The Security Council has already agreed two sets of sanctions against Iran for ignoring its calls to suspend enrichment, and Western powers are now openly talking of a new resolution after Iran missed the latest deadline.

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.