Journalist Roxana Saberi, who was released by Iranian authorities last week, said Thursday she had been under “severe psychological and mental pressure” during interrogations.

“I was under severe psychological and mental pressure, although I was not physically tortured,” she told National Public Radio in an interview on Thursday.

In January, Saberi was arrested and held by Iranian intelligence officials.

Saberi says she did not know why she was arrested.

“It wasn’t for reporting without a press pass. My interrogators claimed that I was spying for the U.S., and however much I told them I was not – that I was simply writing a book and doing interviews for a book, which I hoped to use to show English speakers around the world a more balanced and complete picture of Iranian society – however much I told them this, they told me I was lying and that I was a U.S. spy.”

She said that she made a false confession under pressure, who she says told her that if she didn’t, she would face 10 or 20 years in prison and even execution.

“And I thought, well, if something happens to me, my family doesn't know where I am, maybe they would never find out. And so I made a false confession and I said, Yes, I'm a U.S. spy,” she said.

However she later reconsidered, saying her “conscience go the better of [her].”

After this, she was tried and convicted with a sentence of eight years in prison.

She described the pressure of her interrogations.

“The first few days, I was interrogated for several hours, from morning until evening, blindfolded, facing a wall, by up to four men, and threatened, as I said, that I would be put in prison for 10 to 20 years or more or even face execution. And I was in solitary confinement for several days. The really difficult thing was they didn't let me tell anyone where I was.”