Iran's semi-official ISNA news agency is reporting that the country has transferred an amount of its surplus heavy water to Oman for sale.

The late Sunday report quotes Behrouz Kamalvandi, spokesman for the Atomic Energy Organization of Iran, as saying "In view of the progress of talks with several foreign firms and countries to purchase heavy water, some quantities of Iran's surplus production has been transferred to Oman."

A recent U.N. report said that Tehran had slightly more heavy water in storage than the 130 metric tons allowed by the agreement between Iran and six world powers.

The landmark 2015 nuclear deal went into effect in January to cap Tehran's nuclear activities in exchange for the lifting of economic sanctions.