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An Iranian filmmaker, who said he is engaged to the American journalist jailed in Iran for allegedly spying for the U.S., defended his fiancee as innocent in an open letter and begged Iranian authorities to release her.

The letter by Bahman Ghobadi, circulated by an Iranian human rights group, described 31-year-old Roxana Saberi as an intelligent, hardworking reporter who spent virtually all her time doing research. He also said she had long wanted to leave Iran, but stayed for him.

"I am writing this letter for I am worried about her. I am worried about her health. I heard she was depressed and cried all the time. She is very sensitive," Ghobadi said. "My letter is a desperate call to all statesmen and politicians, and to all those who can do something to help. ... I beg you, let her go! ... I beg you not to throw her in the midst of your political games!"

Saberi, a dual Iranian-American citizen who was born in the U.S. and grew up in Fargo, North Dakota, moved to Iran six years ago and worked as a freelance reporter for several news organizations including National Public Radio and the British Broadcasting Corp.

She was arrested in January and initially accused of working without press credentials. But an Iranian judge later charged her with passing intelligence to the U.S. — a far more serious allegation. She was convicted of spying last week and sentenced to eight years in prison.

Her case has been a source of tension between Iran and the U.S., which has called the charges against her baseless and repeatedly demanded her release. Over the past week, Iranian officials sent signals they may be backing down from holding her in prison for the lengthy sentence.

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Saberi's parents, who live in Fargo but are in Iran to seek her release, could not immediately be reached for comment. Saberi's brother, who also lives in the U.S., said he did not know his sister was engaged but confirmed Ghobadi was her close friend.

Ghobadi's letter, distributed Tuesday by the International Campaign for Human Rights in Iran, said he had known Saberi for years.

"At the beginning of our relationship, she wanted to go back to the United States. She would have liked us to go together. But I insisted (she) stay until my new film was over. She really wanted to leave Iran," his letter said.

Saberi's Iranian-born father has said his daughter was working on a book about the culture and people of Iran, and hoped to finish it and return to the United States this year.

Ghobadi also mentioned her work on the book, saying Saberi was looking for a sponsor and a local publisher for it.

"She was always busy reading and doing her research. Nothing else," he wrote. "Roxana's book was a praise to Iran. ... But why have they said nothing? All those who have talked, worked and sat with her, and who know how guiltless she is."

Ghobadi is an Iranian filmmaker of Kurdish origin. His films, including the 2000 "A Time for Drunken Horses" and 2005 "Half Moon," often deal with the experiences of Iranian Kurds living in the border regions with Iraq, and he has won several prizes at European and Asian film festivals.

Ghobadi said in his letter that he has struggled as a filmmaker in Iran because his movies were banned.