An Iranian court has sentenced the Iranian-American freelance journalist Roxana Saberi, who was accused of espionage, to eight years in jail, her lawyer said today.
"She has been sentenced to eight years ... I will appeal," Abdolsamad Khorramshahitold Reuters.
Saberi, a 31-year-old dual US-Iranian citizen, was arrested in late January and initially accused of working without press credentials.
In a case that threatens to complicate efforts to improve relations between the US and Iran, she was subsequently accused of passing classified information to US intelligence services.
The trial took place behind closed doors.
Washington has dismissed the charges against Saberi, who has reported for the BBC and America's National Public Radio (NPR), as "baseless and without foundation".
The US secretary of state, Hillary Clinton, expressed concern about the case and called for her release.
Freedom House, a US human rights group, said the case was the latest in a string of attacks on press freedom in Iran.
However, Alireza Jamshidi, an Iranian judiciary spokeswoman, today rejected the accusation, saying: "Giving an opinion on a case, by an individual or a government, without being informed about the facts in it, is utterly ridiculous."
Saberi's father, the Iranian-born Reza Saberi, who was in Iran for the trial, said his daughter was finishing a book on Iran and had planned to return to the US this year.
The case comes at a time when the US president, Barack Obama, is trying to improve relations with Iran and make headway in a long-standing dispute over the country's nuclear programme.
The US severed diplomatic ties with Iran after the Islamic revolution in 1979, but Obama has offered to extend a hand of peace if Iran "unclenches its fist".
NPR said Saberi's press credentials were withdrawn more than a year ago but said she had continued to file short news stories, which the Iranian government tolerated.
Saberi, a former Miss North Dakota beauty queen whose mother is Japanese, originally went to Iran six years ago to complete a master's degree on Iranian studies and international relations.
Iran rarely arrests foreign journalists, but foreign nationals with Iranian parents who work as journalists are subject to extra scrutiny and are sometimes harassed.
Her arrest is the latest in a series of detentions of Americans with Iranian backgrounds, apparently amid government fears that the US is trying to use them to foment a "velvet revolution".
According to the Committee to Protect Journalists, Iran has the world's sixth worst record for jailing journalists and detained or investigated more than 30 in 2008.