Iran has increased its stockpile of highly enriched uranium and is refusing to grant inspectors access to a nuclear site where it has reportedly resumed production of advanced centrifuges, according to United Nations nuclear watchdog reports issued ahead of renewed nuclear talks between Tehran and world powers. 

In two International Atomic Energy Agency reports to member states seen by Reuters, the IAEA said Iran prevented inspectors from reinstalling cameras at the Karaj nuclear facility, which was the site of a sabotage attack Tehran blamed on Israel earlier this year. 

Under an agreement reached with the IAEA in September, Iran agreed to allow inspectors to service surveillance equipment at the key manufacturing site. According to the confidential IAEA reports, Iran hasn’t granted inspectors access as promised.  

"This is seriously affecting the Agency's ability to restore continuity of knowledge at the workshop, which has been widely recognized as essential in relation to a return to the [Joint Comprehensive Plan of Action],” read one of the reports.