An American-born journalist accused of spying for the U.S. has been convicted and sentenced to eight years in an Iranian jail, her lawyer said Saturday, threatening to derail fledgling efforts to improve hostile relations between the two nations.

The White House stated that U.S. President Barack Obama said he was "deeply disappointed" on Saturday, as reports surfaced that journalist Roxana Saberi was tried, convicted and sentenced during a one-day, closed door court session.

Roxana Saberi, a 31-year-old dual Iranian-U.S. citizen, was initially arrested in January for allegedly working without a proper press pass.

Since then, however, a member of Iran's hard-line judiciary upped the charge to espionage, which can carry a death penalty in severe cases.

The former Miss North Dakota beauty pageant winner moved to Iran six years ago to write a book about the country.

Reza Saberi, the reporter's Iranian-born father, told National Public Radio that officials tricked his daughter into incriminating herself by promising to let her go if she told them what they wanted to hear.

He added that his daughter -- who has worked for NPR and the BBC -- was convicted by the court on Wednesday. However, officials did not announce the trial's outcome until Saturday, he said.

Reza Saberi said he wasn't allowed into the court to see his daughter and he added that she is "quite depressed" with the outcome.

Saberi's lawyer, Abdolsamad Khorramshahi, told The Associated Press he would "definitely appeal the verdict."

However, the trial and the resulting uproar from human rights groups comes as Washington and Tehran attempt to thaw a relationship that was severed during the 1979 Islamic Revolution.

Obama has clearly spelled out his intention to engage Iran in bilateral talks, which marks a massive foreign policy shift from that of his predecessor George Bush, who advocated a tough, unilateral approach with Tehran.

In return, Iranian President Mahmoud Ahmadinejad has said his country is preparing new strategies to end the standoff with the U.S. and its allies over Iran's nuclear program.

However, Ahmadinejad himself is facing a rocky political future as Iranians prepare to head to the polls in June for presidential elections. Slumping oil prices and sluggish global trade have hit Iran hard and the nation is struggling with persistent inflation and high unemployment.

Still, some Iranian leaders have downplayed Saberi's case and said it would have little effect on relations with the U.S.

"Although there is a wall of mistrust between Iran and the United States, the judicial verdict won't affect possible future talks between the two countries. The verdict is based on evidence," said lawmaker Hosseini Sobhaninia.

However, Saberi's father disagreed, and told NPR that there was no evidence against his daughter.

Human rights groups have said that the conviction is part of a crackdown on the press by conservative factions within Iran.

Dennis Trudeau from the group Reporters Without Borders said the case represents "an extreme sentence" under the Iranian criminal code.

"This is the latest example of how Iranian authorities are using ... spy charges to arrest journalists and make the gag of free expression in Iran even tighter," he told Â鶹´«Ã½net Saturday.

"Roxana Saberi had lost her press card years ago and was a student and was not a journalist anymore in Iran," he said, adding that hardliners are likely attempting to scare other journalists in the country.

"It certainly is a warning to other journalists," he said, adding that Tehran has been cracking down on bloggers, foreign reporters and local journalists.

Canadian relations with Tehran have been strained since 2003, when Canadian-Iranian photojournalist Zahra Kazemi was killed after being thrown in an Iranian jail.

With files from The Associated Press