Iran is developing a second path to a nuclear weapons capability by operating a plant that could produce plutonium, satellite images show for the first time.
The Telegraph can disclose details of activity at a heavily-guarded Iranian facility from which international inspectors have been barred for 18 months.
The images, taken earlier this month, show that Iran has activated the Arak heavy-water production plant.
Heavy water is needed to operate a nuclear reactor that can produce plutonium, which could then be used to make a bomb.
The images show signs of activity at the Arak plant, including a cloud of steam that indicates heavy-water production.
Inspectors from the International Atomic Energy Agency have been unable to visit the facility since August 2011 and Iran has refused repeated requests for information about the site, which is 150 miles south-west of the capital, Tehran.
Western governments and the IAEA have held information about activity at Arak for some time.
But today’s exclusive images are the first to put evidence of that activity into the public domain.
The details of Iran’s plutonium programme emerged as the world’s leading nations resumed talks with Tehran aimed at allaying fears over the country’s nuclear ambitions.
The new images also show details of the Fordow complex, which is concealed hundreds of feet beneath a mountain near the holy city of Qom. At talks in Kazakhstan yesterday, world leaders offered to relax sanctions on Iran in exchange for concessions over Fordow, which is heavily protected from aerial attack.
The striking image of steam over the Arak heavy-water complex is a vivid demonstration that the regime has more than one pathway to a potential nuclear weapon.
Previously, international talks on Iran’s nuclear programme have focused on the Islamic Republic’s attempts to enrich uranium at plants including Fordow.
But the new images of Arak highlight the progress Iran has made on facilities that could allow it to produce plutonium, potentially giving the country a second option in developing a nuclear weapon.
Other images of the area around Arak show that numerous anti-aircraft missile and artillery sites protect the plant, more than are deployed around any other known nuclear site in the country.
The missile defences are most heavily concentrated to the west of the plant, which would be the most direct line of approach for any aircraft delivering a long-range strike from Israel.
Mark Fitzpatrick, a former US State Department official at the International Institute for Strategic Studies, suggested that Arak could be part of a process that might trigger Western strikes on Iran.
One option for the Iranian regime would be to acquire the necessary reprocessing technology from North Korea, he said.
“By then, the option of a military strike on an operating reactor would present enormous complications because of the radiation that would be spread,” he explained.
The Telegraph’s images were analysed by Stuart Ray of McKenzie Intelligence Services, a consultancy firm.
He said: “The steam indicates that the heavy-water plant is operational and the extent of the air defence emplacements around the site make it suspicious.”
Based on its own analysis of satellite images, the IAEA has reached a similar conclusion. In a report distributed to its board last week, the agency reported “ongoing construction” at the Arak site and active heavy water production.
According to the Institute for Science and International Security, a US think tank, if the heavy-water plant reaches full capacity, it would produce about 20lb of plutonium a year.
That could be enough for two nuclear warheads if the plutonium was reprocessed.