Iran's foreign minister has expressed optimism that a visit by UN inspectors to the country's nuclear facilities would produce an understanding, despite world concerns that Iran is trying to build nuclear weapons.
The three-day inspection tour by the International Atomic Energy Agency team that started on Sunday comes during spiking tension. The West is imposing new sanctions to try to force Iran to slow or halt its nuclear programme, and Iran is threatening to close the Strait of Hormuz, a vital oil passage, in retaliation.
Visiting Ethiopia, Iranian Foreign Minister Ali Akbar Salehi appeared to be trying to defuse the crisis.
"We are very optimistic about the mission and the outcome" of the IAEA mission, Salehi was quoted as saying by Iran's semiofficial Mehr news agency. "We've always tried to put transparency as a principle in our cooperation with IAEA," Salehi said. "During this visit, the delegation has questions and the necessary answers will be given,"
The findings from the visit could greatly influence the direction and urgency of US-led efforts to rein in Iran's ability to enrich uranium - which Washington and allies fear could eventually produce weapons-grade material. Iran has declined to abandon its enrichment labs, but claims it seeks to fuel reactors only for energy and medical research.
The team is likely to visit an underground enrichment site near the holy city of Qom, 80 miles south of Tehran, which is carved into a mountain as protection from possible airstrikes. Earlier this month, Iran said it had begun enrichment work at the site, which is far smaller than the country's main uranium labs but is reported to have more advanced equipment.
The UN nuclear agency delegation includes two senior weapons experts - Jacques Baute of France and Neville Whiting of South Africa - suggesting that Iran may be prepared to address some issues related to the allegations that it seeks nuclear warheads.
In unusually blunt comments ahead of his arrival, the IAEA's Deputy Director General Herman Nackaerts - who is in charge of the agency's Iran file - said he wants Tehran to "engage us on all concerns."
Iran has refused to discuss the alleged weapons experiments for three years, saying they are based on "fabricated documents" provided by a "few arrogant countries" - a phrase authorities in Iran often use to refer to the United States and its allies. "So we're looking forward to the start of a dialogue," Nackaerts told reporters at Vienna airport. "A dialogue that is overdue since very long."
The IAEA team wants to talk to key Iranian scientists suspected of working on a weapons programme. They also plan to inspect documents related to nuclear work and secure commitments from Iranian authorities to allow future visits. It is unclear how much assistance Iran will provide, but even a decision to enter a discussion over the allegations would be a major departure from Iran's frequent simple refusal to talk about them.