Jason Rezaian, a Washington Post correspondent, has gone on trial behind closed doors in Iran on charges of spying, in a case that has clouded Iran's rapprochement with the US.

Rezaian's wife, Yeganeh Salehi, who is also a journalist, appeared in court on Tuesday alongside her husband and a female press photographer, Iran's official IRNA news agency reported.

The US criticised the trial's "complete lack of transparency" and renewed calls for Iran to drop "absurd" spying charges.

Rezaian, who is an Iranian-American, was arrested along with Salehi in July. She was freed on bail in October.

At the time of their arrest, Rezaian and Salehi were at their home in Tehran along with two Iranian-US friends who have not been named.

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.

Barred from attending

Rezaian faced the charges with only his attorney present, his brother Ali Rezaian said.

His mother and his wife have been barred from attending the hearing.

"I think the only reason you could possibly imagine that the trial would be closed would be to prevent people from seeing the lack of evidence," Ali Rezaian told Reuters news agency.

Citing his lawyer, the Washington Post said in April that Rezaian faces espionage charges for allegedly collecting confidential information about domestic and foreign policy and handing it to "hostile governments".

Martin Baron, the newspaper's executive editor, said there was "not an ounce" of justice in the proceedings and the "fate of a good, innocent man hangs in the balance".

"Iran is making a statement about its values in its disgraceful treatment of our colleague, and it can only horrify the world community," he said.

Losing weight

According to his family, Rezaian has lost 18 kg in weight while serving time at Tehran's Evin prison.

Mohammad Javad Zarif, Iranian foreign minister, said in April that an intelligence operative, possibly linked to the US government, may have "taken advantage" of Rezaian.

US President Barack Obama has called the charges against Rezaian "vague" and pressed Iran to release all American detainees.

The US criticised on Tuesday the "complete lack of transparency" in the trial of Rezaian, with Bernadette Meehan, National Security Council spokesperson, saying that the Obama administration was monitoring the case "as closely as possible".

"While we call for this trial to be open, we also maintain that Jason should never have been detained or put on trial in the first place," she said.

Source: Al Jazeera and agencies