Iran's enriched uranium stock roughly a third of amount allowed - IAEA

A technician checks valves at the uranium conversian facility in Isfahan, 450 kilometers south of Tehran, February 3, 2007. REUTERS/Caren Firouz (IRAN)

VIENNA (Reuters) - Iran's official stock of enriched uranium has fallen by half after large amounts stuck in pipes have been recategorised as unrecoverable under a process agreed with major powers, the U.N. atomic watchdog said on Friday.

But before that process began last month, Iran came close to reaching a limit on its uranium stock, one of the most sensitive aspects of Tehran's nuclear deal, a confidential report by the International Atomic Energy Agency (IAEA) obtained by Reuters made clear.