An Iranian dissident group accused Tehran on Tuesday of hiding a secret nuclear facility even as US negotiators signaled they're ready to make a concession to reach a deal with Iran on its disputed nuclear program.
In Washington, the National Council of Resistance of Iran showed satellite imagery and photographs of what it said was a secret facility buried several stories under a military base on the outskirts of Tehran. The facility, protected by vault-like doors and anti-radiation shielding, is used for research and development, and advanced machinery produces enriched uranium, said the group's spokesman, Alireza Jafarzadeh.
The secrecy of the program and its underground location are signs that its purpose is "for a nuclear weapons project," said the NCRI's U.S. representative, Soona Samsami.
In pictures: The Nuclear Security Summit 2014
In pictures: The Nuclear Security Summit 2014
1/17 The waiters who got the job
The male waiters prepare the plenary table during a break at the 2014 Nuclear Security Summit on March 25, 2014 in The Hague, Netherlands
2/17 The official group shot
The heads of the delegations pose for an official group photo at the 2014 Nuclear Security Summit on March 25, 2014 in The Hague, Netherlands
3/17 Talk amongst yourselves
US President Barack Obama waves next to Chinese President Xi Jinping as they pose for a family picture with other world leaders, ministers and heads of international organisations on the second day of the two-day Nuclear Security Summit in The Hague on March 25, 2014
4/17 Angela Merkel and Sauli Niinisto
German Chancellor Angela Merkel and Finnish President Sauli Niinisto at an informal plenary at the 2014 Nuclear Security Summit
5/17 The opening session
The opening session of the 2014 Nuclear Security Summit on March 24, 2014 in The Hague, Netherlands.
6/17 Barack Obama and Mark Rutte
US President Barack Obama shakes hands with Dutch Prime Minister Mark Rutte following a press conference at the Gemeentemuseum in The Hague on March 25, 2014 at the end of the Nuclear Security Summit
7/17 The empty chair
German Chancellor Angela Merkel looks at the empty seat of the US president in The Hague on March 25, 2014 on the second day of the two-day Nuclear Security Summit
8/17 Maite Nkoana-Mashabane and Mark Rutte
South African Minister of International Relations and Cooperation Maite Nkoana-Mashabane greets Dutch Foreign Minister Mark Rutte at The World Forum in The Hague on March 24, 2014 on the first day of the two-day Nuclear Security Summit
9/17 View on the opening
A general view of the opening session of the 2014 Nuclear Security Summit on March 24, 2014 in The Hague, Netherlands
10/17 Helle Thorning Schmidt
Danish Prime Minister Helle Thorning Schmidt arrives for meetings on the second day of the 2014 Nuclear Security Summit on March 25, 2014 in The Hague, Netherlands.
11/17 Park Geun-hye and Barack Obama
US President Barack Obama speaks next to South Korean President Park Geun-hye during a trilateral meeting with the Japanese prime minister at the US ambassador's residence in The Hague on March 25, 2014 after they attended the Nuclear Security Summit
12/17 Federica Mogherini and Mark Rutte
Italian Foreign Minister Federica Mogherini speaks with Dutch Prime Minister Mark Rutte during a session on the second day of the Nuclear Security Summit in The Hague on March 25, 2014
13/17 Julie Bishop
Australian Foreign Minister Julie Bishop leaves at the end of the Nuclear Security Summit in The Hague on March 25, 2014
14/17 Ban Ki-moon and Barack Obama
President Barack Obama chats with U.N. Secretary General Ban Ki-moon following the group photo at the 2014 Nuclear Security Summit on March 25, 2014 in The Hague, Netherlands
15/17 Erna Solberg and Helle Thorning-Schmidt
Norway's Prime Minister Erna Solberg, left, and Denmark's Prime Minister Helle Thorning-Schmidt, were two of the seven female leaders present at the summit.
16/17 The G7
The G7 countries took the opportunity to discuss the recent developments in Ukraine during the Nuclear Security Summit. From left to right: President of the European Council Herman van Rompuy, Canadian Prime Minister Stephen Harper, French President Francois Hollande, British Prime Minster David Cameron, U.S. President Barack Obama, German Chancellor Angela Merkel, Japanese Prime Minister Shinzo Abe, Italian Prime Minister Matteo Renzi and President of the European Commission Jose Manuel Barroso
17/17 The royals and Dalia Grybauskaite
Dutch King Willem-Alexander and Queen Maxima greet Lithuania President Dalia Grybauskaite (right), at the Royal Palace Huis ten Bosch in The Hague, Netherlands, 24 March 2014
She called on the United States to demand that Iran provide the United Nations nuclear watchdog agency immediate access to the site.
"If the USA is serious about preventing the Iranian regime from getting nuclear weapons, it must make continuing talks dependent on letting the IAEA (International Atomic Energy Agency) to immediately visit this site," Samsami said.
The NCRI's allegations could not be confirmed, and U.S. officials did not respond to requests for comment. The United States and other Western nations have cited evidence that Iran has harbored a secret weapons program, but Iran denies it.
The new allegations come a day after U.S. negotiators meeting with their Iranian counterparts in Geneva said they had discussed a major U.S. concession: allowing Iran to begin increasing nuclear fuel production after 10 years if Iran sticks to agreed-upon limits during that time period.
Iran has insisted that any steps it takes must be matched by significant and rapid relief from stringent economic sanctions imposed by the West.
The U.S. goal is a deal that prevents Iran from producing enough nuclear fuel to make a bomb for at least a year. The reasoning: Give the United States time to catch Iran cheating and do something about it.
Hossein Mousavian, a former spokesman for Iran's negotiating team, told USA Today the United States will have to accept compromise if it wants a deal.
Iran considers the NCRI a terrorist organization. Clare Lopez, a former CIA analyst at the Center for Security Policy, a Washington think-tank, said the group has a solid track record for revealing secret Iranian nuclear facilities. It first revealed nuclear facilities at Natanz and under a mountain in Fordo and a suspected site at Parchin that has since been razed.
"They can't say Iran should do all the major steps in the first six months, and they will only lift substantial sanctions after 15 years. It's not going to happen," Mousavian said. "Iran is willing to implement all its commitments in the shortest period of time and is suspicious of pushing the comprehensive package for a decade or more."
The new revelation "means (the Iranians) are negotiating in bad faith," Lopez said.
David Albright, a nuclear weapons expert and president of the Institute for Science and International Security, urged caution about the group's claims. "They tend to be good at identifying sites, but usually, they misinterpret their purpose," he said.
This story originally appeared on USA Today. The content was created separately by The Independent.