Among them is Haleh Esfandiari, the head of the Middle East Program of the Woodrow Wilson Institute, and Kian Tajbakhsh a consultant with the Open Society Institute.
Esfandiari and Tajbakhsh were formally charged with endangering national security through propaganda against the system and espionage for foreigners.
U.S. Dismisses Charges
Human rights activists, colleagues, and relatives of the scholars have dismissed the charges as baseless and Washington has described them as "absurd."
U.S. State Department spokesman Tom Casey spoke to reporters in Washington on May 29.
"It's absurd to allege that they are American spies, American government employees, or that anything they've been doing in Iran is driven by American government concerns," he said.
Similar charges have in the past been brought against other intellectuals and human rights advocates who have been detained for long periods of time under difficult conditions.
Political prisoners in Iran, particularly those considered to be a security threat, are isolated and denied access to the outside world. They are held in solitary confinement and subjected to multiple and protracted interrogations.
Former political prisoners in Iran have told RFE/RL that during their detentions they were questioned about their current and past activities, articles that in some cases had been published several years earlier, foreign trips, and other issues.
Mehrangiz Kar, a prominent human rights lawyer who was jailed in Iran in 2000 on security charges, told RFE/RL that she felt during interrogations that one of her "crimes" was her marriage to a well-known journalist, Siamak Purzand.
Kar, who now lives in exile in the United States, said she was held in solitary confinement for several weeks in Tehran's notorious Evin prison, where she had to sleep on the floor wrapped in her chador.
"The cell was very small, it was very dirty, the WC was inside the cell and it was also very dirty," she said. "There was a sink there; I drank the water from it for more than 20 days because I didn't know and then I found out that the water is contaminated."
Authorities denied Kar access to her family or to lawyers. The only window in her cell was blackened and the only people she would meet were prison guards and interrogators who subjected her to vicious verbal attacks and threats.
She continued: "There was mental pressure; there was pressure through long hours of interrogations; there was pressure through an emphasis [by interrogators] that we were working to please foreign elements; there was pressure in other forms, for example [interrogators] would not accept our written statements and we had to write them over [and over] many times."
Ali Afshari, a former student leader, was also subjected to long hours of interrogation during the several times he was detained in Iran in 2000 and 2003. During that time he spent 400 days in solitary confinement.
Afshari, who also resides in the U.S. now, told RFE/RL that he had to endure isolation as well as physical and mental torture. He said he was deprived of sleep and subjected to a mock execution.
He believes authorities use these measures to break the will of the prisoners and force them to act according to their wishes and admit "their crimes."
Threats And Intimidation
"First they describe very difficult circumstances for [the prisoner]," he said. "They say you face the death penalty, your family could face problems, they create fear through different ways. Then someone comes and says: 'there is one way that will prevent you from falling into this precipice, if you should cooperate with us. We're not going to do anything to you, you have become a toy,' and [say others such] things. In this atmosphere the accused [often] drops [his or her] resistance."
Interrogators made Afshari crack and in 2001 he "confessed" -- in front of TV cameras -- to having participated in a campaign aimed at overthrowing the Iranian regime. Shortly after the confessions were aired by Iranian state TV, Afshari publicly retracted them and said he made them under duress.
Abdolkarim Lahidji is the deputy director of the Paris-based International Federation of Human Rights, and he also heads the League for Defense of Human Rights in Iran.
He told RFE/RL he is concerned the 67-year-old Esfandiari and 45-year-old Tajbakhsh could face similar pressure.
"I'm pretty sure that both of them have been under all kinds of pressure and it is possible [authorities] have forced them into [false] confessions but we know that these confessions have no legal value," he said. "I hope they will be released soon and be able to return to their life and work."
Fear Of A 'Soft' Revolution?
Lahidji says he is also concerned with the fate of Radio Farda correspondent Parnaz Azima, who has been prevented from leaving Iran and charged with acting against Iranian security. Azima's U.S. passport was confiscated upon her arrival at Tehran's airport on January 25 to visit her mother.
Some believe the Iranian-Americans have become victims of the growing tension between Tehran and Washington. Others say the arrest of Iranian-American scholars is a sign of Iran's fear of a "soft" revolution.
Esfandiari was detained on May 8. She was about to leave Iran in December after having visited her 93-year-old mother when her Iranian and American passports were stolen. Authorities did not issue her a new passport and instead subjected her to multiple interrogations.
Tajbakhsh was detained around May 11. He has been involved in urban planning and humanitarian assistance and has worked with international organizations such as the World Bank.
A number of scholars and intellectuals in the United States and other countries have called for their release.