VIENNA (Reuters) - Iran has invited U.N. inspectors to visit its Arak heavy-water production plant on December 8, the first concrete step under a new cooperation pact aimed at clarifying concerns about the Islamic Republic's nuclear program.
U.N. nuclear agency chief Yukiya Amano also said it would take some time to look into how Sunday's separate, landmark agreement between Iran and six world powers on curbing Tehran's disputed nuclear activity could be "put into practice" with respect to his inspectors' role in verifying compliance.
Amano, addressing the 35-nation board of the International Atomic Energy Agency (IAEA), suggested that additional financial resources and staff may be needed.
Both agreements indicate how Iran is acting quickly to address fears about its nuclear program after the election in June of a relative moderate, Hassan Rouhani, as new president on a platform to smooth its troubled relations with the world.
The Arak facility produces heavy water intended for use in a nearby research reactor that is under construction. The West is concerned that the reactor, which Iran has said could start up next year, could yield plutonium as fuel for atomic bombs once operational. Iran says it will make medical isotopes only.
As part of its agreement with the powers, Iran is to halt installation work at the reactor and stop making fuel for it.
The IAEA will be able to significantly expand monitoring of Iran's uranium enrichment plants and other sites under the November 24 interim accord reached after marathon talks between Iran and the United States, Russia, China, France, Germany and Britain.
"This will include the implications for funding and staffing," Amano said, according to a copy of his speech.
"This analysis will take some time. I will consult the board as soon as possible when it has been completed."
Western diplomats say the U.N. watchdog, which regularly visits Iranian nuclear sites to ensure that no nuclear material there is diverted for military purpose, will require extra resources to cope with an increased workload.
About 10 percent of its annual 121-million-euro ($164 million) budget for inspections is already devoted to Iran. The agency has about 1-2 staff on the ground every day of the year, with about 20 staff dedicated to inspector activity in Iran.
"There is significant extra work and they will require extra resources to do it," a Western envoy said, with "the extremely complex and difficult implementation" of Sunday's interim accord expected to start in January.
The agreement between Iran and the powers is designed to halt any further advances in Iran's nuclear campaign and buy time for talks on a final settlement of the decade-old dispute.
After years of confrontation, it underlined a thaw in relations between Iran and the West after the June election of Rouhani on a platform to end Tehran's isolation and win relief from sanctions that have battered the oil producer's economy.
But Western officials and experts caution that finding a permanent solution to the Iranian nuclear issue will likely be an uphill struggle, with the two sides still far apart on the final scope and capacity of the Iranian nuclear program.
The Islamic Republic says it is a peaceful energy project but the United States and its allies suspect it has been aimed at developing the capability to produce nuclear weapons.
Iran agreed on Sunday to stop its most sensitive nuclear work - uranium enrichment to a higher fissile concentration of 20 percent - and cap other parts of its activities in exchange for limited sanctions relief.
Refined uranium can fuel nuclear power plants but also the fissile core of a bomb if processed to a high degree.
"The IAEA inspectors are able to give an early warning if Iran does not comply at these locations with its undertakings," former IAEA chief inspector Olli Heinonen said. "In verification work, the devil is in the detail."
The IAEA's visit in 10 days' time to the heavy water production plant near the town of Arak is part of a separate agreement signed this month between the U.N. agency and Iran.
Inspectors have not been there since August 2011, despite repeated requests. But Iran agreed on November 11 to grant access to this site and to a uranium mine within three months. The IAEA needs to visit such places as part of its mandate to ensure that a country's nuclear program is peaceful.
Another Western diplomat described these Iranian concessions to the IAEA as "low-hanging fruit" and said Tehran would need to take more important steps in future, including addressing agency suspicions that it has researched how to assemble nuclear weapons. Iran denies this allegation.