European Union and Iranian officials will discuss the standoff over Tehran's nuclear programme today.
Iran reiterated it would not bow to UN Security Council demands to suspend uranium enrichment over Western fears it is developing nuclear arms. The oil exporter says its nuclear programme is only for power generation.
Iranian chief nuclear negotiator Ali Larijani will hold talks in Madrid with EU foreign policy chief Javier Solana, who is acting for world powers, on the dispute that has already seen Iran hit twice with UN sanctions.
Foreign ministers of the Group of Eight leading industrialised nations, meeting in Germany yesterday, expressed "deep regret" that Iran had carried on expanding enrichment activities.
UN Security Council resolution 1747 gave Tehran a 60-day deadline to freeze all enrichment, a process of purifying uranium for power plants or weapons. Iran ignored the deadline, which expired last week.
Besides major Western powers and Japan, the G8 also includes Russia, which has backed previous UN resolutions in the past while stressing Iran's right to a peaceful nuclear programme.
Mr Larijani told reporters in Tehran: "We have no conditions, and we are ready for constructive talks but we will not accept any preconditions. We are ready to remove concerns over Iran's atomic issue."
Mark Fitzpatrick, a nuclear non-proliferation analyst, said: "I do not expect much [at the meeting]. The two sides remain very far apart."
He said Mr Solana would be looking to see if Mr Larijani was ready to suggest the "freeze for freeze" idea - enrichment suspension for sanctions suspension - that Iran floated with Swiss interlocutors earlier this spring.