The United States, Germany, France, Britain, Russia and China issued a statement at a meeting of the International Atomic Energy Agency (IAEA) after Iran raised the stakes in the row by announcing it would accelerate sensitive nuclear work.
Washington’s envoy said separately that Iran’s plan to speed up enrichment with a more advanced model of centrifuge machines in a mountain bunker showed its “brazen” and deepening defiance of international demands to curb the activity.
Enrichment can yield energy for electricity or, if extended to a higher degree, material for nuclear bombs.
Iran’s representative hit back at a tense IAEA board meeting, vowing the Islamic state would resist Western pressure over a nuclear program it says has exclusively peaceful aims.
Ambassador Ali Asghar Soltanieh also launched a verbal attack on IAEA Director-General Yukiya Amano and accused him of bias, highlighting increasingly strained relations between Tehran and the UN nuclear watchdog.
The Japanese IAEA chief has taken a blunter approach to Iran than his predecessor Mohamed ElBaradei, saying in his first report on the country early last year that he feared it may be working to develop a nuclear-armed missile.
“He is not doing his job. Instead, with his reports, he is paving the way for more confrontation between member states,” Soltanieh told reporters.
But the six powers — including Russia and China who have been less inclined to try to isolate Iran — united to throw their weight behind Amano, who last month asked Tehran to provide access to sites and officials to help answer the agency’s queries. Iran rebuffed the request.
The six powers said Iran’s “consistent failure” to comply with obligations under UN resolutions to restrain nuclear activity and allow more effective IAEA inspections had “deepened concerns” about its intentions.
“We call on Iran to cooperate fully with the agency,” a joint statement read out at the closed-door session said.
“Outstanding issues need to be resolved in order to exclude the existence of possible military dimensions to Iran’s nuclear program.” It did not mention Iran’s plan to expand enrichment.
The statements at a session of the IAEA’s 35-nation governing board came a day after Iran announced a plan to triple its capacity to produce higher-grade uranium.
Iran also said on Wednesday it would transfer the production of the material from its Natanz enrichment complex to a nascent, smaller site in a bunker, one seen as better protected from possible US or Israeli air strikes, at Fordow later this year.
Western powers are concerned about the higher-grade enrichment because it takes Iran a step closer to producing potential atomic bomb-grade fuel. Tehran denies such aims and says its nuclear program is for peaceful uses only.
US envoy Glyn Davies said the plan was Iran’s “most recent brazen example of its deepening non-compliance.”
He added in a board statement: “Iran’s efforts to develop a nuclear warhead ... should demand the undivided attention of the international community.”
Iran only disclosed the existence of Fordow, near the Shiite Muslim holy city of Qom, in September 2009, after Western intelligence agencies had detected it.
The United States and Israel, Iran’s arch-adversaries, have not ruled out military action to knock out Iranian nuclear assets if diplomacy fails to resolve the eight-year-old dispute.
Iran’s refusal to halt enrichment — a process that can make material for bombs if done to a much higher level — has drawn four rounds of UN sanctions rounds on the major oil producer.
Iran says it is refining uranium to the 3.5 percent level for electricity production and to 20 percent purity for medical applications.
But its decision last year to raise the level of enrichment beyond that needed for power plant fuel to 20 percent increased disquiet in the West because this would bring Iran significantly closer to the 90 percent threshold suitable for bomb fuel.
