Ms Saberi has been in Iran for six years, working and doing research
An Iranian-American journalist accused of spying in Iran went on trial this week and a verdict is expected soon, an Iranian official has said.
"The first trial meeting on Roxana Saberi was held yesterday [Monday]," judiciary spokesman Ali Jamshidi told a news conference in Tehran.
"I think the verdict will be announced soon, perhaps in the next two or three weeks," the official added.
Ms Saberi, 31, is being held in Evin prison near Tehran.
She worked briefly for the BBC three years ago. She has also worked for the American public radio network NPR and the TV network Fox News.
She has been in custody in Tehran since late January.
Ms Saberi originally faced the less serious accusations of buying alcohol, then working as a journalist without a valid press card, but last week Iranian prosecutors accused her of spying for the US.
Raised in Fargo, North Dakota, by Iranian father and Japanese mother
Wins state beauty pageant before studying at Northwestern University in Chicago, and Cambridge University in the UK
2003: arrives in Iran as a freelance reporter for BBC and Fox News among others
2006: Iran authorities revoke her press credentials
January 2009: arrested in Tehran for buying wine
April 2009: tried for espionage
The Justice Ministry said she is being tried in a closed hearing of Iran's revolutionary court, which handles national security cases.
US Secretary of State Hillary Clinton has demanded her release.
Mr Jamshidi criticised the US state department for saying the accusations against Ms Saberi were "baseless".
"That a government expresses an opinion without seeing the indictment is laughable," he said.
No more details of the case have been released, and Ms Saberi's lawyer says he has been told not to speak to the media.
A US-Iranian national, Ms Saberi has spent six years in Iran studying and writing a book.
Her parents arrived in Tehran earlier this month and were allowed to see her for 20 minutes. According to her lawyer, they found her in good health and good spirits.