International Atomic Energy Agency chief Yukiya Amano on Tuesday indicated his suspicion that Iran might be pressing ahead with nuclear activity applicable to development of weapons, the Associated Press reported.
The sides have sought unsuccessfully for more than a year to set the terms for resuming the U.N. organization's probe of Iran's atomic operations. The agency is particularly interested in gaining access to the Parchin military base, which is suspected of having housed experiments that could be used in development of atomic arms.
Tehran says its nuclear work has no military component and that the Parchin site is not involved in its atomic sector.
"We do not know for sure, but we have information indicating that Iran was engaged in activities relevant to the development of nuclear explosive devices in the past and now," Amano said in an interview with AP. This was seemingly his most direct claim that sensitive nuclear efforts are ongoing in Iran.
The agency's data was "cross checked ... so we have concerns," he added.
Tehran has repeatedly requested to review the data, which it alleges is not real. The nation "should be presented with any such evidence so it can respond to it," said physicist Yousaf Butt of the James Martin Center for Nonproliferation Studies.
Amano expressed his agency's readiness "to continue ... the dialogue" with Iran. He said there is "some possibility" that Iran might be building uranium enrichment plants beyond the two known sites at Natanz and Qum; Tehran has previously said 10 more plants are planned.
Iran is scheduled on Friday to begin another round of nuclear talks with world powers China, France, Germany, Russia, the United Kingdom and the United States. The sides are considering a deal under which Iran would receive select concessions, including a reduced restriction on sales of petrochemical goods, in exchange for measures including halting enrichment of uranium to 20 percent.
"I remain always cautiously optimistic. But I am also very clear that it is very important that we do get a response (from Iran)," Reuters quoted European Union foreign policy chief Catherine Ashton, who has led the talks on behalf of the six powers, as saying on Wednesday.
Meanwhile, a new analysis from the Carnegie Endowment for International Peace and the Federation of American Scientists said Iran has lost "well over $100 billion" due to curbed petroleum sales and lost business with other nations resulting from its nuclear program, Reuters reported.
Use of military force is not likely to resolve the long-running standoff, according to the analysis. "Given the country's indigenous knowledge and expertise, the only long-term solution for assuring that Iran's nuclear program remains purely peaceful is to find a mutually agreeable diplomatic solution," the report says.