Vienna: The US accused Iran of deception and defiance on Wednesday, asserting that over the past decade it has stonewalled international demands to allow scrutiny of its nuclear programmes.
The European Union was also critical of Iran, as the 35-nation board of the International Atomic Energy Agency focused on the failure of attempts to persuade the Islamic Republic to reduce fears about its nuclear activities.
One concern is Tehran`s refusal to heed UN Security Council demands that it stop uranium enrichment and construction of a reactor that will produce large amounts of plutonium. Both can be used to arm nuclear weapons.
The other is the failure of IAEA attempts to restart its investigation of allegations that Iran has worked directly on developing such weapons. That probe has been stalled for more than six years, and 10 rounds of Iran-IAEA negotiations over the past 18 months have failed to revive it.
Iran says all of its nuclear programmes are peaceful and insists the allegations of weapons work are based on forged intelligence from its enemies. It was expected to respond to the new criticism later in the day.
US envoy Joseph Macmanus said the lack of progress "documents Iran`s longstanding practice of deception and noncompliance," while an EU statement described Iran`s "procrastination" as unacceptable.
The EU said it is deeply concerned about Iran`s enriched uranium programme and a reactor that will produce plutonium when finished.
An earlier statement by the US and five other world powers was less forceful, reflecting the sensibilities of China and Russia. While joined with the United States, Britain, France and Germany in trying to negotiate with Iran on its nuclear programme, those two nations are traditionally less critical of Tehran for strategic and economic reasons.
The six said it is "essential and urgent" that Iran reaches an agreement with the IAEA that will allow the agency to investigate suspicions Iran worked on nuclear weapons.
They said IAEA access to Parchin is particularly important. The agency has tried vainly over its 18 months of negotiations to visit the suspected site of weapons-related experiments.
Beyond fears that Tehran may have worked on atomic arms, most international concern has focused on its uranium enrichment, because this is further advanced than the reactor and already has the capacity to enrich uranium to weapons-grade.
But fears now are growing about the reactor at Arak, in central Iran, which Tehran says will be operational by next year.