Azerbaijan, an ally of the United States, has acknowledged the delay. The Azeri government said it has sought to determine whether the nuclear shipment violated United Nations Security Council sanctions on Iran.
Iran has also reported the construction of a second nuclear reactor. Officials said the facility was being built along the Iranian border with Iraq and would have a capacity of 360 megawatts.
"Now we need to think about the fuel for it," Iranian ambassador to Russia, Gholamreza Ansari, said.