It was the second time Tehran had surpassed the 130 metric tonne threshold for heavy water, a material used in reactors like Iran's unfinished one at Arak
Iran has sent some "surplus" heavy water to Oman, an Iranian nuclear spokesman was quoted as saying on Sunday, after a U.N. atomic watchdog said Tehran was over a soft limit set under its nuclear deal with major powers.
"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," said Behrouz Kamalvandi, spokesman for Iran's Atomic Energy Organization, according to the Iranian Students' News Agency (ISNA).
ISNA said Kamalvandi told the agency that more heavy water would be sent to Oman as talks with overseas buyers made progress. He did not give details.
There was no immediate official confirmation of the report.
The United States and Iran clashed openly at the UN atomic watchdog on Thursday for the first time since they signed the landmark nuclear deal last year, differing over Tehran's repeated testing of one of the deal's less strictly defined limits.
It was the second time Tehran had surpassed the 130 metric tonne threshold for heavy water, a material used in reactors like Iran's unfinished one at Arak, since the deal was put in place in January. Heavy water reactors can more efficiently produce plutonium, which can be used in weapons.
Iran had 130.1 tonnes of the material, the International Atomic Energy Agency (IAEA) said in a confidential report seen by Reuters.
The IAEA said Iran was preparing to ship some heavy water out of the country to get back under the 130-tonne limit, but the U.S. ambassador to the agency said Tehran would not be in compliance until that heavy water had been delivered to a foreign buyer as the deal requires.
Iran has close ties with its Gulf Arab neighbour Oman, which has often helped Tehran by facilitating contacts with Western powers with whom the Islamic republic has tense relations.