Ms Saberi worked for the BBC for a few months in 2006
An Iranian-American journalist detained in Iran since January has been accused of spying by Iranian prosecutors.
Roxana Saberi, who is being held in Evin prison in Tehran, will appear in court next week, her lawyer said.
US Secretary of State Hillary Clinton said she was "deeply concerned" about the news.
Ms Saberi originally faced the less serious accusations of buying alcohol, then working as a journalist without a valid press card.
Her parents arrived in Tehran at the weekend and were allowed to see her for 20 minutes. According to the lawyer, they found her in good health and good spirits.
The journalist, 31, 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.
A number of UK and US media outlets, including the BBC, have called on Iran to allow independent access to her.
Mrs Clinton has appealed for her release on more than one occasion.
Her lawyer, Abdolsamad Khorramshahi, said he could not comment on the accusation of spying as he had not been allowed to see the legal papers.