Tehran - New charges have been brought against four US citizens who have been detained in Iran on suspicion of espionage, ISNA news agency reported Tuesday. ISNA quoted judiciary spokesman Ali Reza Jamshidi as saying that the deputy prosecutor of Tehran has found new evidence against the detained Iranian-Americans which required further investigation.
No further details of the charges were given.
Jamshidi had earlier described as "serious" the initial charges of "offending national security" - a euphemism for espionage - brought against the four.
The detainees include Haleh Esfandiari, Middle East director of the Woodrow Wilson International Centre for Scholars in Washington, and Kian Tajbakhsh, a sociologist and urban planning consultant with George Soros' Open Society Institute.
Also charged with national security offences is Ali Shakeri, a peace activist and board member at the University of California.
A fourth detainee, Parinaz Azima, a correspondent for a Persian- language radio station owned by Radio Free Europe and funded by the United States, is not jailed but cannot leave the country.
Nobel Prize-winning lawyer Shirin Ebadi represents Esfandiari but says she that has no access to her client. The Iranian judiciary denies Ebadi's protest.
Iran's press has been linking the case of the four detainees to that of five detained Iranian diplomats in Iraq, and speculating about a plan for a possible exchange deal. Tehran has several times denied any connection between the two cases.
Under Iranian law, only the nationality of the father is acknowledged. The nationality of the mother or second nationalities are not considered.
Most think-tank organizations in the US as well as the Iranian press and media abroad are considered by Tehran as opposition, and seen mostly as aiming to topple the Islamic state.
