A senior Russian diplomat says that Iran has met a key requirement of a nuclear deal with six world powers by completing the transfer of most of its enriched uranium to Russia.

The diplomat spoke to The Associated Press on Monday. He demanded anonymity because he was not authorized to be cited by name.

Under the July 14 deal, Iran must ship out all except 300 kilograms (over 660 pounds) of the close to nine tons of low-enriched uranium it has stockpiled. Low-enriched uranium is suited to power generation but can be further enriched to arm nuclear warheads.

Its removal is a key obligation taken on by Iran under the deal, which aims to reduce its ability to make nuclear weapons — something Tehran says it has no interest in.