An exiled opposition group claimed Monday to have uncovered a new underground nuclear military site in Iran and urged world powers to force Tehran to drop all enrichment at this week's talks in Geneva.
The Paris-based National Council of Resistance of Iran said its sources in the country had confirmed the existence of the military site, codenamed "012", but the group said it could not be certain of what was happening inside the highly secure area.
The NCRI has revealed important aspects of Iran's nuclear programme in the past, including the existence of the Natanz facility in 2002, but experts have met many of its other claims with scepticism.
"The clerical regime (in Iran) continues its secret and undeclared projects.... It has set up scores of secret and underground facilities," the NCRI's Mehdi Abrishamchi told journalists.
He said the newly uncovered site was located at the Haft-e Tir military compound, about 10 kilometres (six miles) from the central city of Mobarakeh in Isfahan province.
The site was located inside a 600-metre (650-yard) tunnel, contained four galleries and was heavily guarded, he said.
Work on the project began in 2005, construction of the tunnels was completed in 2009 and work on facilities at the site "has been nearly completed," he said.
The NCRI said its information was based on "multiple intelligence assets... inside Iran," including "dozens of sources within the clerical regime," Abrishamchi said.
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He said the site was being operated by a secret nuclear weaponisation agency known as SPND and run by senior Iranian scientist Mohsen Fakhrizadeh, who it claimed was in charge of the regime's alleged atomic weapons programme.
"Given that this site was built and is supervised by the SPND... there is certainty of the fact this site is linked to the military aspect" of the nuclear programme, Abrishamchi said.
The NCRI could not, however, confirm the purpose of the site.
"It could be an area for research or other aspects," he said. "We have no intelligence on the installation, for example, of centrifuges."
He said the information had been passed on to French authorities and the Vienna-based International Atomic Energy Agency "in the last few days".
"The clerical regime is in the process of constructing and completing a series of secret sites.... Site '012' is one of them," he said.
Abrishamchi said any agreement between world powers and Tehran and its nuclear programme that does not include "a complete halt in enrichment" would "provide time to the regime to obtain the nuclear bomb".
Negotiations between Iran and the so-called P5+1 -- Britain, France, the United States, Russia and China plus Germany -- resume in Geneva on Wednesday after an earlier round of talks this month came close to an interim deal but stumbled on last-minute changes to a draft text.
The powers suspect Iran is using its nuclear programme to develop atomic weapons but Tehran insists it is purely for peaceful purposes.
The NCRI is the political umbrella for a number of dissident groups, in particular the People's Mujahedeen of Iran (MEK), founded in the 1960s to oppose the rule of the Shah.