EU foreign ministers, at a meeting in Luxembourg, welcomed Washington's new attitude, saying it creates a "window of opportunity" for talks on Iran's atomic programme and other issues.

"The EU calls upon Iran to seize this opportunity to engage seriously with the international community in a spirit of mutual respect, in order to find a negotiated solution to the nuclear issue," they said in a statement.

Such a solution "will address Iran's interests, including the development of a civil nuclear power generation programme, as well as the international community's concerns.

"The evolution of our relations with Iran will also depend on it."

However Iranian President Mahmud Ahmadinejad, in a television interview broadcast Sunday, said that his country was not ready to talk to the United States unconditionally.

"We should just have a clear-cut framework for talks," he said.

Those comments came a day after Iran's supreme leader Ayatollah Ali Khamenei blamed the United States and Israel for persistent violence in Iraq after two suicide attacks left scores of Iranian pilgrims dead.

Western powers fear that Iran's nuclear drive could be a cover for efforts to build an atomic bomb, but Tehran insists it is aimed purely at generating electricity for a growing population.

The Europeans have been struggling since 2006 to persuade the Islamic republic to accept a package of political and economic incentives in exchange for an end to uranium enrichment.

Enrichment is a process for powering a nuclear reactor, but at highly refined levels the uranium can be used to build the core of an atom bomb, which many countries fear the Islamic Republic is trying to covertly develop.

Iran, which is labouring under three sets of UN sanctions, has refused to sit down at the negotiating table if it has to suspend uranium enrichment even before the talks begin.

While Washington is offering dialogue, US Secretary of State Hillary Clinton said Wednesday that the new administration of President Barack Obama would be prepared to push for tough new sanctions against Iran if the dialogue fails.