A British-Greek journalist released from jail in Iran said Friday that he had been blindfolded, held in solitary confinement and subjected to frequent interrogations.

Iason Athanasiadis said the corridors of Tehran's main Evin prison had been filled with demonstrators arrested during massive rallies that followed Iran's disputed June 12 presidential election.

He said he was held there for 18 days and questioned for alleged spying.

"It was full to bursting with people who had been arrested in the street riots," Athanasiadis said in an interview with The Associated Press after his return to Athens, where his parents live.

"There were people sitting in rows on the floor; ... there were others being interrogated at little desks in the corridor because the interrogation rooms were full," he said.

"I heard questions and shouts coming from the interrogation rooms and the occasional slap."

Athanasiadis said he was detained and questioned by officials from Iran's Intelligence Ministry and was generally treated well, except for being slapped once during an early interrogation.

He was released July 5 after petitions from the Greek government.

Athanasiadis, 30, who speaks Farsi, is a freelance reporter who had been working for The Washington Times.

He said he was kept alone in a continually lit 5-foot by 8-foot (1.5-meter by 2.5-meter) cell and subjected to about a dozen lengthy interrogations, most while blindfolded.

Athanasiadis said he was blindfolded and told to turn his head to the wall whenever he left his cell to be questioned.

He still managed to sneak glimpses of the crowded corridors, he said.

Athanasiadis said that his interrogators showed him a 2005 photograph of himself chatting with a British diplomat as proof of his suspicious behavior. They also pointed to romantic text messages on a mobile phone he had borrowed from a friend; messages he said were to the friend who owned the phone.

"It was really a sort of Alice-in-Wonderland situation at times," he said. "At the end of the interviews, they were quite chummy and we were talking about philosophy. ... At this point they had all pulled on surgical masks so we could look each other in the eye."

Athanasiadis said his interrogators eventually apologized to him for taking so long, explaining they had been busy with the demonstrations.

"The way the system seems to work there is that if someone is suspicious then (security forces say) 'we'll just take him in'."

He said he was arrested by armed and plain-clothed men at Tehran Airport, who punched him and pushed him to the ground when he tried to alert other passengers to his detention.

He said an American woman who was a bystander at the airport wrote down his details and later telephoned his editor in Washington, D.C.

On Wednesday, Athanasiadis met with Greek Foreign Minister Dora Bakoyannis and thanked her for playing a key role in ending his imprisonment.

He also thanked Ecumenical Patriarch Bartholomew I, spiritual leader of the world's Orthodox Christians, for his appeal to Iranian authorities.

"There was an amazing show (of support) by Greek diplomacy, also using unorthodox and interesting pressure points," he said.

"The Ecumenical Patriarch coming up in my support is something I'm going to be eternally grateful for."