Iran's stockpile of low-enriched uranium has increased in the past three months despite Tehran's commitment to reduce it significantly under its deal with major powers, the U.N. nuclear watchdog said on Wednesday, in a confidential report seen by Reuters. The International Atomic Energy Agency report noted that Iran's stockpile of low-enriched uranium had increased by 460.2 kilograms (1,014.6 pounds) to 8,305.6 kilograms (18,310.7 pounds). Under the deal, that stockpile must be slashed to no more than 300 kilograms (661 pounds). However, one senior diplomat said the increase was a normal fluctuation. The report also showed that Iran has significantly reduced the number of centrifuges meant to enrich uranium, which can produce nuclear fuel, isotopes for research, or the core of an atomic bomb, depending on the degree of enrichment. It said 11,308 centrifuges were standing at Iran's main enrichment center as of Nov. 15, about 3,000 fewer than previously. It also noted cuts at a smaller facility, for a total reduction of about 4,500 of the nearly 20,000 machines Iran had previously set up. But the diplomats familiar with the report said all of the machines that have been taken out were previously idle. Thousands of centrifuges that were spinning uranium into enriched levels used for fuel are no longer online but remain on standby and can be restarted at short notice. Under the terms of the July 14 deal, Iran is allowed to keep 5,060 centrifuges operating to enrich at levels significantly below weapons-grade and at concentrations normally used to generate energy. That is about half of the number it had running before adoption day. Two diplomats who spoke to The Associated Press had differing takes on the efforts to dismantle centrifuges. One said that it is normal to start the cutbacks with the machines that have never been put to work, because the process of removing the ones that have been enriching is more complex. But the other noted that the Iranians have publicly linked full implementation of the deal to another report meant to put to rest the issue of allegations that Tehran worked in the past on atomic arms. Those Iranian officials have said Iran will not enact meaningful cuts in its enrichment program or other activities that could be used to make nuclear arms -- as the July 14 deal foresees -- until that second report is published next month. After fending off IAEA attempts to investigate the suspicions of a nuclear arms project for more than a decade, Tehran agreed to cooperate with the agency under the condition that it delivers a final report that would put the issue to rest. Iran was promised sanctions relief under the July 14 deal. Beyond cutting back on uranium enrichment in return, it must also re-engineer a reactor to reduce its output of plutonium, another pathway to an atomic bomb. Implementation day for both sides to show they have abided by their commitments is expected to be early next year.