Washington Post journalist Jason Rezaian and his wife Yeganeh Salehi during a press conference in Tehran, Iran, on Sept. 10, 2013. (EPA)

An Iranian court could be nearing the end of its trial of a detained Washington Post journalist on charges that include espionage, his lawyer said Monday, amid increasing calls for his release after nearly a year in custody.

The international media freedom group, the Committee to Protect Journalists, joined The Post’s executive editor in separate demands to end Jason Rezaian’s detention and halt the prosecution.

Rezaian, The Post’s Tehran correspondent, will mark one year in custody Wednesday as he faces a closed-door trial in Tehran’s Revolutionary Court on allegations that include spying-related claims — charges he has strongly denied.

The 39-year-old Rezaian, who holds dual U.S.-Iranian citizenship, had his third hearing before the court last week. The next session has not been scheduled, but his lawyer, Leila Ahsan, said court officials told her it will “almost certainly” be the last.

“Still, it’s not clear how long it will take for the court to issue a verdict on the case after the last session,” Ahsan told the Associated Press in Tehran.

Jason Rezaian’s journey has taken him from a childhood in San Francisco to his father’s native Iran. At 37, he became the Washington Post correspondent in Tehran. In July 2014, he was thrown into Iran’s Evin Prison, where he remains. This is his story. (This video has been updated to reflect recent developments in the Rezaian case.) (Jorge Ribas/The Washington Post)

She declined to comment further and is barred from publicly discussing details of the proceedings. Rezaian could face between 10 and 20 years in prison if convicted.

“It is long past time for the Iranian authorities to bring this process to an end,” Martin Baron, The Post’s executive editor, said in a statement. “There can be no reason for further delay.”

Baron called the Iranian charges “grave” but said they “could not be more ludicrous.”

“Any fair outcome would clear Jason of these manufactured charges so that he can be released and reunited with his family,” Baron said.

In a separate letter, the New York-based Committee to Protect Journalists appealed to the head of Iran’s judiciary, Sadegh Larijani, to intervene to ensure that the case “is resolved immediately and that Jason returns to his family.”

“Never before has an international journalist been held for so long in the Islamic Republic of Iran,” said the letter, sent on behalf of the group’s board of directors. “Our colleague has been denied any real opportunity to defend himself against the charges.”

Top U.S. officials, including Secretary of State John F. Kerry, have raised concerns about Iran’s detention of Rezaian and several other Americans. The issues have remained separate from a deal reached last week to limit Tehran’s nuclear program, but President Obama said the jailed Americans remain a priority for Washington.

“We are working every single day to try to get them out and won’t stop until they are out and rejoined with their families,” Obama told reporters Wednesday.

Rezaian, his Iranian wife and two photojournalists were detained on July 22 last year in Tehran. His wife, Yeganeh Salehi, a correspondent for the National newspaper in Abu Dhabi, was later released on bail. One of the photojournalists also faces charges related to the case.

Some of the claims against Rezaian appear to stem from a visit he made to a U.S. consulate seeking a visa for his wife and a letter he wrote seeking a job in the Obama administration in 2008 — material that was apparently taken from his confiscated laptop.

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