Her father told the Reuters news agency in an interview last Tuesday he believed she would starve herself to death if the verdict was upheld by an appeal court.

Saberi was sharing a cell with two other female prisoners, her father said, and was "not in a bad condition, but physically frail and "desperate to get out of there".

A citizen of both the United States and Iran, Saberi was arrested in late January for working in the Islamic Republic after her press credentials had expired. She was later charged with espionage.

Calls for release

Earlier on Saturday, Abdolsamad Khorramshahi, Saberi's defence lawyer, told the Iranian Student's News Agency he had appealed against the jail sentence.

He said he believed the case would be forwarded to an appeal court next week and he hoped for either an acquittal or a reduction in the jail term.

Saberi had been working on a book about the culture and people of Iran [AFP]
Mahmoud Ahmadinejad, the Iranian president, had called on the general prosecutor to ensure that Saberi enjoys full legal rights to defend herself. The judiciary chief has said her appeal must be dealt with "in a careful, quick and fair way".

Barack Obama, the US president, has expressed deep concern for her safety, urging Tehran to release her.

Hillary Clinton, the US secretary of state, has said releasing Saberi, who has worked for the BBC and US National Public Radio, would serve as a goodwill gesture.

Iran, which does not recognise dual nationality, says Washington should respect the independence of Iran's judiciary.

Reporters Without Borders, the Paris-based media rights group, has called Saberi's conviction "unjust under the Iranian criminal code", saying it was a warning to foreign reporters working in Iran before its presidential election in June.

Saberi, who was born in the United States and grew up in Fargo, North Dakota, moved to Iran six years ago and worked as a freelance journalist.

Her father said Roxana, who was Miss North Dakota in 1997, had been working on a book about the culture and people of Iran, and hoped to finish it and return to the United States this year.

She received Iranian citizenship because her father was born in Iran.