"Larijani recognized that Biden's speech and his support for multilateralism seemed to be very positive," the spokeswoman told AFP after Larijani held talks with Spanish Prime Minister Jose Luis Rodriguez Zapatero in Madrid.

Larijani, a former nuclear negotiator, told Zapatero that Vice President Joe Biden had enunciated "an important change in US foreign policy" during a weekend speech, added the spokeswoman, who was not quoting Larijani directly.

Speaking at an international security conference in Munich, Germany on Saturday, Biden said the United States was open to dialogue with Iran, which Washington and its Western allies believe is aiming to develop atomic weapons under the guise of a civilian nuclear energy programme.

"We will be willing to talk to Iran, and to offer a very clear choice: continue down the current course and there will be continued pressure and isolation; abandon the illicit nuclear programme and your support for terrorism and there will be meaningful incentives," he said.

Iran denies its nuclear programme is military in nature and has continued with uranium enrichment, insisting it is only being done to generate electricity.

To convince Iran to suspend the project, major powers have offered a series of political and economic incentives.

Biden's comments mark a change in US policy from former presdient George W. Bush, who once labelled Iran a member of an "Axis of Evil." US-Iran relations have been frozen for three decades.