By Fredrik Dahl
VIENNA (Reuters) - Iran faced Western pressure on Wednesday to speed up its promised cooperation with a long-stalled U.N. nuclear watchdog investigation into suspected atomic bomb research by Tehran, something the Islamic state denies.
The United States, the European Union and others welcomed at a meeting of the International Atomic Energy Agency signs that Iran has begun engaging with the IAEA inquiry but they also made clear Tehran must do much more to fully address their concerns.
U.S. officials say it is vital for Iran to resolve the IAEA's questions if parallel negotiations between Tehran and the United States, France, Germany, Britain, China and Russia on long-term accord are to succeed. Those talks aim to set verifiable, civilian limits to Iran's nuclear activity and end punitive international sanctions imposed on Tehran.
The IAEA has long been investigating suspicions that Iran may have coordinated efforts to process uranium, test explosives and revamp a ballistic missile cone in a way suitable for a nuclear warhead. Iran says the allegations are false but has offered to help clarify them since pragmatist Hassan Rouhani took office as Iranian president last year.
Iran's envoy to the IAEA made clear his view that this would take some time: "These issues are very complicated. Everything should be done in due course," Reza Najafi told reporters.
The EU - which groups three of the six powers seeking to negotiate a settlement to a decade-old dispute with Iran over its nuclear program - noted that "some" progress had been made in the separate talks between Iran and the IAEA.
But, the 28-nation bloc added in a statement to a quarterly meeting of the IAEA's 35-nation governing board, "We call on Iran to provide all the relevant information to the agency, to address fully the substance of all of the agency's concerns and to accelerate its cooperation with the agency."
Canada's ambassador to the Vienna-based IAEA put it more bluntly, saying Iran was using a kind of "salami-slicing way" in its dealings with the U.N. watchdog. "We are definitely of the view that Iran is moving too slowly to address these long-standing questions," Mark Bailey told Reuters.
Adding to the pressure, Group of Seven leaders meeting in Brussels this week are to call on Iran to cooperate fully with the IAEA and "resolve all outstanding issues", according to a draft statement read to Reuters by an EU diplomat.
Tehran says its uranium enrichment program is a peaceful energy project whereas the West fears it is covertly oriented to developing a nuclear weapons capability. Western diplomats have long accused Tehran of stonewalling the IAEA's investigation.
Najafi, the Iranian ambassador, said his country does "not recognize those unsubstantiated allegations" about a secret atomic bomb agenda.
Tehran's talks with the IAEA and with the big powers are complementary as both focus on suspicions it may have secretly sought the means and expertise to assemble nuclear weapons.
After years of rising tension with the West - and fears of a new Middle East war erupting - last June's election of Rouhani paved the way for a dramatic thaw in relations. However, the sides remain far apart on what a final nuclear agreement should look like, with a self-imposed July 20 deadline approaching.
The IAEA inquiry into what it calls the possible military dimensions to Iran's nuclear program focuses on whether the country has worked on designing a nuclear warhead.
IAEA Director General Yukiya Amano said this week that Iran had started to engage substantively with the U.N. agency's investigation, but that more was needed.
U.S. Ambassador Joseph Macmanus said a resolution of the issues related to the investigation was critical and he urged Iran to "further intensify its engagement" with the IAEA.
"Only with Iran's complete cooperation...would the agency be in a position to reach a conclusion regarding whether Iran's nuclear program is exclusively peaceful," Macmanus said.
Last month, Iran gave the U.N. watchdog information it had requested about one of the issues covered by the IAEA's inquiry. Exploding Bridge Wire (EBW) detonators can be used, among other things, to set off an atomic explosive device. Iran also agreed to address two other areas of the investigation by Aug. 25.
Western capitals, aware of past failures to get Iran to cooperate with the IAEA, regard Iran's increased readiness to cooperate as positive but are likely to remain skeptical until it has fully addressed all allegations of illicit atomic work.
"Such engagement is welcome – if long overdue," Macmanus told the IAEA board said about Iran's provision of EBW information to the agency, adding this was "only a first step".
(Additional reporting by Justyna Pawlak in Brussels; Editing by Mark Heinrich)