ISTANBUL, Turkey (CNN) -- Iason Athanasiadis' ordeal began at the airport, shortly after he checked in for his flight to leave Tehran. Iason Athanasiadis said he endured hours of questioning over several weeks in sound-proofed rooms by interrogators he could not see. "I was heading to the gate," the Greek-British journalist said. "This guy materialized on my right. He said 'are you Iason Fowden?' [Athanasiadis' passport name]. I said 'yeah that's me.' He said 'please step to the side ... you're not going to be flying tonight.'" It was an ominous introduction to Iran's security apparatus. Athanasiadis spent the next 21 harrowing days in Iranian prisons, accused of espionage, subjected to interrogations and, on several occasions, beatings.
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Iason Athanasiadis arrested at Tehran airport on June 19
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Journalist had been on assignment for the Washington Times
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Spent the next 21 harrowing days in Iranian prisons accused of espionage
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Released after intense diplomatic effort by Greek government
Tehran
Tehran
The young freelance reporter realized he was in serious danger at the airport in @placeholder on June 19, when a half dozen plain-clothed security officers arrived and began leading him out of the building.
Iran
Iranian
Iranian
International human rights organizations estimate thousands of Iranians have gone missing, since the @placeholder government launched its crackdown on opposition activists and journalists following the disputed June 12 presidential elections.
Tehran
Tehran
Eyewitnesses in @placeholder say many families are still struggling to determine the whereabouts and official status of their detained relatives.
Tehran
Tehran
That night, Athanasiadis says security officers forced him to ride into @placeholder from the airport, with his head buried in his lap.
Tehran
Tehran
Later, when he tried to make a phone call from a police station in @placeholder, Athanasiadis said security forces tackled him, threw him to the ground, beat him with a club and pepper-sprayed him.
Iran
Iranian
Iranian
"The lesson I take from this is that the @placeholder," Athanasiadis said, "have decided to start arresting foreigners."