VIENNA (Reuters) - The U.N. nuclear watchdog sent its top brass to an Iranian embassy event in Vienna last week, but the goodwill gesture likely won't be enough to win over Tehran to transparency about its nuclear activity at crunch talks in Tehran next week.
The attempt by the International Atomic Energy Agency to reach out, with the rare presence of IAEA chief Yukiya Amano and two deputies at an embassy reception marking the 1979 Islamic Revolution, was hailed as "positive" by state media in Tehran.
But Western diplomats, who largely shunned the invitation, doubt that such conciliatory language will translate into any major progress in talks between the Vienna-based U.N. agency and Iran scheduled for February 20-21 in the Islamic state's capital.
The outcome, following an inconclusive first round of discussions last month, could determine whether the long-running international stand-off over Iran's uranium enrichment programme escalates or offers scope to reduce tensions.
"I haven't heard of any movement or cause for optimism on this Iran visit," one Western envoy said.
Still, Amano is clearly determined to do everything he can to persuade Iran to stop stonewalling an investigation by his inspectors and answer mounting suspicions that Iran's enrichment campaign is covertly geared to yielding atomic bombs.
"They are making sure that they are not giving any excuse to Iran not to engage with them," one European diplomat said.
It was no coincidence, he said, that Amano showed up with traditional rice dishes and non-alcoholic drinks for the buffet dinner at the Iranian ambassador's residence on the 33rd anniversary of the ouster of the U.S.-backed shah.
While the IAEA normally dispatches at least one of its top officials to member states' national day receptions, the simultaneous attendance of Amano and deputy directors-general Herman Nackaerts and Denis Flory is uncommon.
Their presence contrasted with the absence of Western diplomats, who mostly stayed away in a sign of Tehran's deteriorating relations with their capitals, with the exception of a few mid-ranking officials from smaller European countries.
The message was not lost on official Iranian media.
"The presence of the agency's top officials was interpreted by other diplomats as an important and positive sign with regard to Iran's nuclear issue," Iran's English-language state television Press TV said on its website.
But this, Western diplomats say, does not alter the fact that the IAEA faces a steep uphill task in getting Iran to cooperate with its inquiry into allegations that the country is looking into "weaponising" enrichment, Western diplomats say.
They say Iran, which has come under tightening sanctions aimed at blocking its oil exports, may agree to make limited concessions at next week's meeting in Tehran to try to blunt growing international pressure on the major crude producer.
But this would fall far short of an "open book" stance by Iran that they say the IAEA would need to assuage concerns that Tehran is honing the means and technologies to assemble nuclear weapons, if its leadership decides to do so.
The Islamic Republic says it is refining uranium only for civilian energy, not nuclear weapons.
Tensions in the nuclear row are soaring in the absence of meaningful diplomacy, with the United States and European Union adopting oil sanctions and Tehran threatening retaliation by closing the Strait of Hormuz, the main Gulf oil shipping lane.
Many are worried about a downward spiral towards military conflict in the Gulf and rocketing oil prices if diplomacy and sanctions fail to change the Islamic state's nuclear course.
The U.N. agency wants Iran to explain intelligence findings - detailed in an IAEA report in November - about research and development pointing to a nuclear weapons agenda, and grant access to sites, documents and people relevant to the inquiry.
It has drawn up a list of steps it wants Iran to take, including granting visits to the Parchin military site mentioned in its report, but Tehran has yet to endorse this plan.
The Islamic Republic has indicated readiness for the first time to address the agency's questions but also repeatedly dismissed the allegations as baseless and forged, doing little to counter scepticism about its intentions.
Western capitals suspect Iran is just trying to buy time by offering "talks about talks" while it accumulates higher-enriched uranium in a mountain bunker that may be largely invulnerable to air strikes, mooted by the United States and Israel as a last resort if diplomacy and sanctions fall short.
Tehran says its drive to stockpile enriched uranium is entirely peaceful and aimed at generating electricity using a future network of nuclear power plants.
Amano told Reuters in Mexico City on Tuesday he hoped for "good, constructive" talks but did not know whether Iran would grant access to the military complex southeast of Tehran.
"Parchin is not the only issue. Our objective is to clarify all the other issues and this cannot be done overnight but we hope that there will be a concrete outcome," he said.
The European diplomat said he hoped for a positive Iranian response to the IAEA's "wish list." But, it would be ridiculous to believe "that the agency will show up and suddenly Iran will give them access left, right and centre."
Mistrust runs deep both in Iran and the West, dimming any prospect for a resolution soon of the dispute.
Iran is convinced the United States ultimately seeks the overthrow of its hardline clerical system of rule.
Iran's Supreme Leader, Ayatollah Ali Khamenei, "believes that the United States is after nothing less in Iran than regime change", former Iranian nuclear negotiator Hossein Mousavian wrote in an article for the Foreign Affairs magazine.
"The door to rapprochement is closing. To keep it from slamming shut, the United States should declare, without conditions, that it does not seek regime change in Tehran."
Editing by Mark Heinrich