The European Union has turned down an offer from Iran to tour its nuclear facilities, EU foreign affairs chief Catherine Ashton said, but remains optimistic about talks with Tehran later this month.

Iran has sent letters to a number of ambassadors to the International Atomic Energy Agency in Vienna, inviting them to visit two sites - the Natanz uranium enrichment plant and the Arak heavy water complex - in the coming weeks.

Diplomats from Britain, France, Germany and the United States were not invited. But Hungary, which holds the rotating presidency of the European Union until July, was invited, leaving the EU in a quandary over what to do.

'What I'll be saying is the role of the inspections of nuclear sites is for the IAEA and I do hope Iran will ensure that the IAEA is able to go and continue and fulfil its work,' Ashton told Reuters after talks with Hungarian Foreign Minister Janos Martonyi, saying the invitation would be declined.

While the United States and the three EU powers most involved in applying pressure on Iran to suspend its uranium enrichment were snubbed by Tehran, Russia and China, which are also involved in sporadic nuclear talks with Iran, were invited.

Ashton said she had consulted with Russia and China before deciding that the invitation should not be accepted.

'I obviously coordinated with the other members of the E3+3 (six powers) who were invited. My view is that though this is not an invitation that I'm taking a negative view of, it's not our job, and looking at the sites and establishing what they are requires expertise,' Ashton said, referring to IAEA inspectors.

'I'm looking forward to the talks with Iran. The Iranians have been helpful in supplying the dates and making that work.
We're working now on what we should do in terms of substance.'

Other invitees for the tour included Egypt, Cuba, Venezuela, Brazil, Turkey, Algeria and the Arab League, diplomats said.
Cuba and Venezuela are allies of Iran, while Turkey and Brazil have tried to mediate in Iran's standoff with big powers.-Reuters