The head of the UN nuclear watchdog has said he expects to sign a deal with Iran soon on investigating suspected weapons activities connected to the country's nuclear programme.
Yukiya Amano, director-general of the International Atomic Energy Agency (IAEA), said on Tuesday in Vienna that he reached an agreement with Iran's government after talks in Tehran, but failed to seal the deal because of "remaining, unspecified differences".
Amano also said that Saeed Jalili, Iran's chief nuclear negotiator, had assured him that "the existing differences will not be an obstacle to the agreement".
The IAEA wants access to sites, officials and documents to shed light on activities in Iran that could be used to develop the capability to make nuclear weapons, especially at the Parchin military complex southeast of Tehran.
Amano said that access to the Parchin military site would "be addressed".
Iran has repeatedly said that Parchin is not a designated nuclear site and thus it is not obliged to permit IAEA inspections. Iran has rejected Western accusations that it is removing evidence at the site.
Scepticism over deal
Some Western diplomats have voiced dissatisfaction with the outcome of Amano's latest negotiations with Iran.
One diplomat told the AFP new agency that there had been "no breakthrough" in Amano's visit.
Another said the trip appeared disappointing but that they were waiting for a "clearer picture" at meetings in the Austrian capital later on Tuesday.
Israel, which like the US has not ruled out air attacks to stop Iran's atomic progress if it deems diplomacy has failed, has said it is "highly sceptical" about the latest agreement between the IAEA and Iran.
Amano met the head of Iran's nuclear energy organisation, Fereydoun Abbasi-Davani, hours after his pre-dawn arrival on Monday, according to ISNA news agency.
After the talks, Abbasi-Davani's office issued a statement saying issues were raised "in a frank manner and proposals were made to remove ambiguities and to develop co-operation", AFP news agency reported.
During his visit, Amano also met Ali Akbar Salehi, Iran's foreign minister, in advance of a crucial meeting on Iran's nuclear-weapons programme in Baghdad on Wednesday between Iran and a group of world powers.
In Baghdad, the powers' main goal will be to get Iran to stop the higher-grade uranium enrichment it started two years ago and has since expanded, shortening the time needed for any weapons bid.
Iran says it needs the uranium enriched to a fissile concentration of 20 per cent for its medical research reactor.
No notable progress
Two meetings between Iran and senior Amano aides in Tehran in January and February failed to make any notable progress.
Such a deal would also not be enough to allay international concerns. World powers want Iran to curb uranium
enrichment, which can have both civilian and military purposes.
Iran insists its nuclear programme is intended only to generate electricity and other civilian uses.
Unlike Israel, assumed to have the Middle East's only nuclear arsenal, Iran is a signatory to treaties that oblige it to work with the IAEA.
Leaders of the G8, worried about the effect of high oil prices on their faltering economies, raised the pressure on Iran on Saturday, conveying their readiness to tap into emergency oil stockpiles this summer if tougher new sanctions on Tehran strain supplies.
By promising co-operation with UN inspectors, diplomats say Iran might aim for leverage ahead of the broader negotiations, where the US and its allies want Iran to halt works they say are cover for developing nuclear weapons.
Western sanctions on Iran's energy exports, and threats by Israel and US of military action, have pushed up world oil prices.