Tajbakhsh is a social scientist, specializing in urban planning, who was working in Tehran as a consultant for the Open Society Institute, a nongovernmental organization created by U.S. financier and philanthropist George Soros.
He is the third Iranian-American facing security-related charges in Tehran to be released by Iranian authorities this month, following the release from prison of Haleh Esfandiari and Tehran's decision to allow Radio Farda correspondent Parnaz Azima to leave the country.
A spokeswoman from the Open Society Institute says Tajbakhsh remains in Tehran for now after reportedly posting bail of about $100,000.
Mohammad Ali Dadakhah, a prominent Iranian lawyer who cofounded the Tehran-based Center of Human Rights Defenders with Nobel Peace Prize winner Shirin Ebadi, told Radio Farda today that under the provisions of Iranian law, Tajbakhsh was imprisoned for too long without a trial.
"It's very joyful news that finally Kian Tajbakhsh was released from prison," Dadakhah said. "Based on Iranian laws, temporary arrest should last only two months unless the court finds new reasons to prolong the temporary arrest, and the accused does not protest" against the reasons for the prolongation, he said.
Tehran is still holding Iranian-American peace activist and businessman Ali Shakeri on security charges.
Shakeri serves on the Community Advisory Board of the Center for Citizen Peacebuilding at the University of California, Irvine. He reportedly was arrested at Tehran's international airport while trying to leave the country for Europe. In June, Tehran confirmed that Shakeri was imprisoned. His family says they have been informed that Shakeri is in solitary confinement at Tehran's notorious Evin prison.
Tehran's deputy prosecutor has said that Shakeri's case was not related to the cases against other Iranian-Americans who have been charged with acting against Iran's national security.
Last month, in the last official word about Shakeri's case, the deputy prosecutor said, "The time had not yet arrived for providing full information about his situation."
Shakeri's son, wife, colleagues, and human-rights groups have all expressed concern about his fate. Shakeri's son said he sounded very depressed in a short telephone call to his family while in detention.
Meanwhile, the case of an American national in Iran remains unresolved. The whereabouts of former FBI agent Robert Levinson have been unknown since he disappeared during a visit to Kish Island off the southern coast of Iran on March 8. According to Levinson's family, he had gone to Kish on business to seek information about cigarette smuggling.
Safely Out Of Iran
On September 3, Tehran allowed scholar Haleh Esfandiari to return to the United States after she had spent several months at Evin Prison.
Esfandiari heads the Middle East Program at the Woodrow Wilson International Center for Scholars in Washington. Charged with acting against Iran's national security, Esfandiari was released from prison on August 21 after she posted bail of about $320,000.
RFE/RL correspondent Parnaz Azima had been virtual prisoner in Tehran since authorities seized her passport in January while she was visiting her ailing mother.
Though Azima was charged with acting against Iran's national security, she was never incarcerated. She returned to the United States on September 18 after she posted bail of about $300,000.
(Radio Farda contributed to this