VIENNA (Reuters) - Iran has dismissed criticism by the International Atomic Energy Agency of its refusal earlier this year to let one IAEA expert into the country as part of a team investigating allegations of nuclear weapons research.
Tehran said it had a sovereign right to decide who to admit onto its territory. But its failure to issue a visa to an IAEA official, who diplomatic sources said was probably a Western atomic bomb expert, may deepen longstanding Western suspicions that it is stonewalling the U.N. agency's inquiry.
The IAEA said last month that Iran had not issued a visa for one member of a team that visited Tehran on Aug. 31 to try to advance the investigation into what the U.N. agency calls the possible military dimensions of the country's nuclear programme.
It was the third time the person, whom the U.N. agency did not identify, had been unable to obtain an entry permit. It was unclear whether this official had received one to join an IAEA delegation holding talks in the Iranian capital this week.
It is important, the IAEA said in a Sept. 5 report on Iran's nuclear programme, that "any staff member identified by the agency with the requisite expertise is able to participate in the agency's technical activities".
But, in a statement distributed to IAEA member states this week, Iran said that granting visas was "our sovereign national right and we will issue it when we deem it appropriate".
The IAEA has for years been trying to get to the bottom of allegations that Iran has worked on designing a nuclear bomb.
Iran says its nuclear activity is a peaceful, but suspicions in the West that the civil nuclear programme is a front for weapons development have led to punishing economic sanctions, which Tehran hopes will be lifted if ongoing negotiations with world powers succeed in ending the standoff.
IAEA member states have the right to deny access to individual inspectors proposed by the U.N. agency, and Iran has for several years blocked staff from some Western nations, including the United States, to check its nuclear sites.
A separate, high-level IAEA team in charge of the Iran inquiry - which at least on some occasions has included officials from France, the United States and Britain - has held several meetings in Tehran since early 2012, including one this week.
Iran said it had provided visas on time to three new members of the IAEA team in recent months.
Western officials say Iran needs to cooperate with the IAEA inquiry if it wants to reach a breakthrough diplomatic settlement with world powers.
Last month's IAEA report said Iran had failed to answer questions about possible military dimensions of its nuclear program by an agreed Aug. 25 deadline, in a possible setback for the farther-reaching diplomacy between Iran and the United States, France, Germany, Britain, China and Russia.
Iran rejects the accusations as baseless. But it has promised, since relative pragmatist Hassan Rouhani was elected president last year on a platform to end its international isolation, to work with the IAEA to clear up the suspicions.
"We continue to cooperate with the IAEA on some of the ambiguities in order to clarify and resolve them," said the Iranian communique to IAEA member countries, which was dated Sept. 19 but only posted on the IAEA's website this week.
While the powers seek to limit the size of Iran's future nuclear program - and thereby extend the time it would need for any attempt to accumulate fissile material for a weapon - the IAEA is investigating purported research and experiments in the past that could be applied to making the bomb itself.
Underlining a determination to press ahead with efforts to modernise its nuclear capacity, an area of concern for the United States and its allies, Iran's statement said it had installed a new, advanced centrifuge, the IR-8, last year in a research and development wing of its Natanz enrichment plant. Centrifuges refine uranium, a nuclear fuel which can have both civilian and military applications.
It said the IR-8 was a "complete new centrifuge" and criticised the IAEA for calling it a "casing" in its reports. If Iran were to successfully replace its current, breakdown-prone IR-1 model, it could amass potential bomb material much faster.
Editing by Mark Heinrich