TEHRAN - Iran will sell part of its stock of heavy water to the United States under its nuclear deal with world powers, an official at the Atomic Energy Organization of Iran (AEOI) announced on Tuesday.

Ali Asghar Zarean also denied reports that Iran had dismantled the core of its Arak nuclear reactor, a key step in the deal that will see sanctions lifted in exchange for temporary limits on Iran’s nuclear activities, AFP reported.

“Iran will sell 40 tons of its excess heavy water to the United States through a third country,” said Zarean, the AEOI deputy chief.

“Six tons of the exported heavy water will be used in nuclear facilities and the rest in American research centers,” he said.

Iran has a heavy water production plant in its Arak nuclear site, which has been operating for several years.

Under its July deal with the 5+1 group -- the United States, Britain, China, France, Russia and Germany -- Iran has agreed to replace the core of the Arak heavy water reactor and take other steps to ensure it cannot be used to make nuclear weapons.

Reports emerged on Monday that Iran had removed the core at Arak, but Zarean said this was not the case and that Tehran was still working on an agreement for a replacement being redesigned with the help of China and the United States.

“We must have a solid agreement with the foreign side, including China.... The documents of the agreement will be officially exchanged at the end of next week or this week,” Zarean said.

“As long as the agreement is not finalised, we will not take any physical measures to remove the core of the Arak reactor.”