Iran has begun dismantling centrifuges at its two main uranium enrichment sites in accordance with a deal struck with major powers this summer, the UN nuclear watchdog said on Wednesday in a confidential report seen by Reuters.Under the July deal, sanctions against Iran will be lifted in exchange for restrictions being placed on its nuclear activities, including slashing the number of centrifuges it has in operation and reducing its stockpile of uranium.The report by the International Atomic Energy Agency (IAEA) to its Board of Governors said Iran had begun moving centrifuges at Fordow and Natanz, its two main enrichment sites. A senior diplomat said the machines were being dismantled."They have been dismantling centrifuges that did not contain hexafluoride," the senior diplomat said, referring to uranium hexafluoride, the feedstock for centrifuges, which can enrich uranium to purities at which it is used as fuel in power stations or, potentially, weapons.Under the July deal, Iran agreed to reduce its number of installed centrifuges to around 6,100 from 19,000, according to the United States. Of the remaining 6,100, only about 5,100 will be used to enrich uranium.The IAEA report said around 4,500 centrifuges had been removed from their positions at Natanz and Fordow.Iran's stockpile of low-enriched uranium had increased by 460.2 kg in the past three months to 8,305.6 kg, the report said. Under the deal, that stockpile must be slashed to no more than 300 kg, but the senior diplomat said the increase was a normal fluctuation."There is nothing special in that. Its the normal way," he said.