Iran has formally charged two Iranian- American academics currently in jail in Tehran with espionage.
Esfandiari has been prevented from leaving Iran since December
A judiciary official said a third Iranian-American, Nazi Azima, who works for Radio Free Europe, faced the same allegations but had not been arrested.
No trial date has been announced and the investigation against all three continues, the official said.
The BBC's Tehran correspondent says the arrests of dual nationals have sparked unease in Iran.
Those in contact with foreigners now fear they too may be accused of spying, Frances Harrison reports.
The judicial spokesman, Ali Reza Jamshidi, said both Haleh Esfandiari and Kian Tajbakhsh were formally charged with spying, acting against Iran's national security and conducting propaganda against the Islamic Republic.
Sixty-seven-year old Haleh Esfandiari runs the Middle East section of the Woodrow Wilson centre in Washington and was in Iran to visit her elderly mother.
Her American and Iranian passports were stolen by armed men as she was on her way to the airport in December 2006, and then, after months of interrogations, she was arrested three weeks ago.
The official said she is in the section of Evin Jail run by the intelligence ministry - which is where political prisoners are normally kept and interrogated.
Kian Tajbakhsh is also a well-known academic and social scientist who had carried out some work for the Open Society Institute of George Soros - an organisation Iran says was trying to instigate a "velvet revolution" to topple the clerical regime.
The judicial spokesman said he had no news of another Iranian American academic, Ali Shakeri, who disappeared earlier this month while in Iran.
One influential newspaper had reported Mr Shakeri was also under arrest.
Although the jailed academics are well-known figures in Iran, nobody has dared defend them here for fear of being accused of spying, our correspondent says.
The arrests have also prompted some Iranians abroad to cancel trips back home - worried they are no longer safe.