BERLIN — A German reporter says he was beaten by guards during his nearly five months of imprisonment in Iran and that he heard constant, "horrible cries" of other inmates being tortured.

In the first public comment since being freed a year ago, Marcus Hellwig told the Sunday mass-circulation tabloid Bild am Sonntag he was regularly beaten and constantly interrogated during the first 10 "brutal" days in captivity until a German diplomat intervened.

"Sometimes they claimed that I was a spy, then allegedly a terrorist," he was quoted as saying. "They wanted to unsettle me with their never-ending questioning, wanted to put me under psychological pressure and create an ambiance of fear," he said.

Hellwig and German photographer Jens Koch — both working for Bild am Sonntag — had entered Iran on tourist visas and were detained in October 2010 after interviewing the son of Sakineh Mohammadi Ashtiani, an Iranian woman sentenced to death by stoning for adultery.

Her case had generated widespread international outrage.

The two journalists were freed a year ago after German Foreign Minister Guido Westerwelle traveled to Tehran for a rare meeting with Iranian President Mahmoud Ahmadinejad, then brought the pair home on his government plane.

Iranian resistance groups later criticized Westerwelle's Tehran visit as a propaganda victory for the Iranian regime.

Hellwig said that prison guards, in an apparent move to frighten him, took him "to a torture cell to show me what they were using there to torture people."

"I was beaten. And there were some other things, but I do not want to talk about them," he said.

Hellwig told the newspaper another torture cell was located near where he and Koch were being held and that they heard its victims throughout the day. "The cries were horrible," the reporter said.

In Tehran, Iranian judiciary officials were not immediately available on Sunday to comment on Hellwig's account of his captivity.

Hellwig said he and the photographer knew that reporting from Iran with tourist visas "would not be without danger, but I had hoped to minimize the risk with good preparation."

Last year, the Iranian judiciary found the pair guilty of committing unspecified acts against Iran's national security. But a court then threw out the journalists' 20-month prison sentence, commuting it to a $50,000 fine.

Hellwig said he and Koch were shocked when prison guards suddenly told the two journalists they were free to go and gave them back their personal belongings. "I only felt free when the government plane left the Iranian airspace heading to Turkey," Hellwig was quoted as saying.

He has written a book about his ordeal entitled "Inshallah. Captive in Iran," which will be published in German later this month. Inshallah is Arabic for "God willing."

Meanwhile, Ashtiani — who was convicted of adultery in 2006 following the murder of her husband — remains behind bars in Iran and authorities said in December she may be hanged. In July 2010, Iran suspended plans to carry out her death sentence by stoning following an international outcry about the case.

Ali Akbar Dareini in Tehran, Iran, contributed to this report.