Iran's Arak heavy water reactor is incapable of producing plutonium for use in a nuclear weapon, a major fear of the West, Tehran's atomic chief said Friday.

"The Arak research reactor cannot produce plutonium that could be used to make an atomic bomb since the plutonium will remain in the reactor's core for a year," Ali Akbar Salehi told the ISNA news agency.

"Plutonium destined to make a weapon cannot stay there for more than three or four weeks or it will contain other elements preventing its use" for military means, he said.

"Anyway, Iran does not have a reprocessing plant" to purify plutonium for such use, Salehi insisted.

Under a landmark deal struck on November 24, Iran agreed to roll back or freeze parts of its controversial nuclear drive for six months in exchange for modest sanctions relief and a promise by Western powers not to impose new sanctions.

The Arak site is of concern to the West because Tehran could theoretically extract weapons-grade plutonium from its spent fuel if it also builds a reprocessing facility.

Iran agreed not to build such a facility as part of last month's nuclear deal. It also committed not to make further advances at its Arak, Fordo and Natanz facilities.

"When International Atomic Energy Agency cameras are installed and constantly monitoring the reactor and inspectors can visit, there will no longer be cause for concern," Salehi said.

Salehi has said dismantling the Arak reactor or giving up uranium enrichment is "a red line which we will never cross."

Western powers and Israel suspect Iran's nuclear activities mask military objectives, despite Tehran's repeated insistence that they are entirely peaceful.