Washington Post correspondent Jason Rezaian went on trial behind closed doors in Iran Tuesday on charges of spying, a case that has clouded a rapprochement with the United States.
Rezaian's wife, Yeganeh Salehi, who is also a journalist, appeared in court alongside her husband and a female press photographer, Iran's official IRNA news agency reported.
The trial is being held in Branch 15 of the Tehran revolutionary court, which usually presides over political cases or those related to national security.
Rezaian, an Iranian-American, has been held since July last year in a politically sensitive case that has unfolded while Iran and world powers conduct nuclear talks.
His wife, who worked for The National, an English-language newspaper based in Abu Dhabi, was arrested along with him but released on bail after spending two and a half months in custody.
Rezaian, 39, is accused of "espionage, collaboration with hostile governments, gathering classified information and disseminating propaganda against the Islamic republic," according to his lawyer Leila Ahsan.
The United States and the Washington Post have branded the charges absurd and demanded his release.
Tehran does not recognise dual nationality, and says the case is a purely Iranian matter.
State media gave no details of Tuesday's hearing and no indication of how long the trial might last.
But it will overlap with the final stretch of negotiations between Iran and the major powers aimed at reaching a comprehensive agreement on Tehran's nuclear programme by a June 30 deadline.
Rezaian's case has been played out in the Iranian media, where he has been accused of spying and passing information about Iran to US government officials.
Among the offences he is alleged to have committed is writing a letter to US President Barack Obama.
The Post's executive director, Martin Baron, said the newspaper had tried to obtain a visa for a senior editor to travel to Iran but its request was never acknowledged by the Iranian authorities.
"There is no justice in this system, not an ounce of it, and yet the fate of a good, innocent man hangs in the balance," he said.
"Iran is making a statement about its values in its disgraceful treatment of our colleague, and it can only horrify the world community," he added.
Rezaian has been held in the capital's notorious Evin Prison and his family have frequently spoken of their fears for his health, citing his need for medication to combat high blood pressure.
His American mother, Mary, has been in Iran for the past two weeks awaiting the trial. There was no immediate word on whether she had been permitted to attend.
California-born Rezaian is one of four US citizens that Obama has urged Iran to return home, with the support of the US Senate.
The other detained Americans are pastor Saeed Abedini, in jail for more than two years after being convicted of undermining national security, and former US Marine Amir Hekmati, who is serving a 10-year sentence for cooperating with hostile governments.
A fourth American, retired FBI agent Robert Levinson, remains missing after mysteriously vanishing in Iran eight years ago.