UN nuclear inspectors arrived in Iran on Saturday to visit the Arak heavy water plant for the first time in more than two years, AFP reports, citing the Iranian ISNA news agency.
The visit comes just weeks after Iran clinched a landmark nuclear agreement with world powers, under which it will freeze or curb some of its controversial nuclear activities in return for limited relief from crippling international sanctions.
The Arak heavy water plant had been a sticking point in the negotiations because, once completed, it would produce plutonium as a by-product, potentially giving Tehran a second route to a nuclear weapons capability.
Satellite images from almost a year ago showed that the plant was operational, raising fears that it is trying to produce plutonium for a nuclear bomb.
The two inspectors from the International Atomic Energy Agency (IAEA) will begin their work on Sunday at the site, 240 kilometers (150 miles) southwest of the capital, but ISNA did not say how long they would be there.
Shortly after the nuclear deal was signed in Geneva, Iran invited inspectors to visit the Arak plant.
During the Geneva talks, Iran’s interlocutors - the United States, Russia, China, Britain, France and Germany - wanted Tehran to halt all work on the facility related to the production of plutonium that can be used to develop an atomic bomb. Iran claims that the reactor, which it has said could start up next year, will produce medical isotopes.
Iran's atomic energy organization said it had provided the IAEA with "required information on ongoing research" about its new generation of centrifuges - machines used to enrich uranium by spinning it at supersonic speed.
Spokesman Behrouz Kamalvand said the information was supplied "on time and within the framework of safeguard agreements," the official IRNA news agency reported.
The IAEA has visited Arak before, but says it has not received any new design details since 2006. Inspectors last visited the heavy water plant in August 2011.
Israeli Prime Minister Binyamin Netanyahu has repeatedly said that the agreement that was signed with Iran is dangerous and will allow Tehran to continue its nuclear program and give nothing back to the West while being rewarded with sanctions relief.
This position has placed the Netanyahu at odds with the U.S. administration, to the point where President Barack Obama reportedly told him to “take a breather” from his criticism and shift attention to the terms of the final deal still under negotiation.
Both Obama and Secretary of State John Kerry, who took part in the nuclear talks in Geneva, defended the deal on Saturday as they spoke at the Saban Forum in Washington.
Obama said that the best way to prevent Iran from getting a nuclear weapon is “through a comprehensive, verifiable, diplomatic resolution," but stressed that all options remained on the table.
Kerry, who gave the keynote address at the forum several hours later, acknowledged that Iran with a nuclear weapons posed a "real" existential threat to Israel, but argued that the interim deal reached in Geneva would make Israel safer.