The Washington Post's Jason Rezaian at The Washington Post on November 6, 2013. (Zoeann Murphy/The Washington Post)

Five weeks after being charged in a Tehran court, Jason Rezaian, the Washington Post journalist imprisoned in Iran, still does not know the exact nature of the allegations against him and remains unable to speak to a lawyer, the reporter’s family said after visiting him twice last month.

In what appears to be the longest imprisonment for a Western journalist in Iran, Rezaian, who has been the newspaper’s Iran bureau chief since 2012, has been held at Tehran’s Evin prison for more than 170 days. Weeks after an initial court date, he is aware only that the five separate charges against him relate to alleged “activities outside the bounds of journalism,” said his mother, Mary Breme Rezaian, and his brother, Ali Rezaian.

His family called on Iran’s government to permit Rezaian, a dual U.S.-Iranian citizen, access to a lawyer and to make the allegations against him public.

“The fact of the matter is that they have since the beginning bent or broken their rules, and ignored the constitutional requirements that they have, in how they handle a detainee,” his brother said.

“Jason is aware of that, and it’s very frustrating for him,” Ali Rezaian said. “That’s part of what’s causing him so much stress and difficulty.”

The Washington Post has repeatedly called for the immediate release of Rezaian, who was accredited to work as a journalist in Iran. Washington Post Executive Editor Martin Baron underscored the paper’s concern about Rezaian’s detention in a year-end note to staff.

“We feel outrage at the severe injustice endured by Jason Rezaian, our cherished correspondent, who has been imprisoned for many months in Iran on unspecified charges,” Baron wrote.

The Obama administration has also appealed for Rezaian’s release, and Secretary of State John F. Kerry has raised his case with Iranian officials during international talks over Tehran’s nuclear program.

Kerry is expected to meet with Iranian Foreign Minister Mohammad Javad Zarif in Geneva this week during the latest round of talks. Zarif has previously called Rezaian a “fair reporter” and said he “had hoped all along that his detention would be short.”

Rezaian, who was born and raised in California, was arrested on July 22 along with his wife, Yeganeh Salehi. But he was not officially charged until a court session on Dec. 6. His family said that Rezaian, who speaks Farsi but does not read or write the language, was provided a court interpreter who ostensibly spoke English but was unable to adequately communicate the charges that were being presented.

“He’s still not 100 percent sure” what the charges are, Ali Rezaian said. “There’s never been any specific accusation of wrongdoing.”

Salehi, an Iranian national and fellow journalist, was released on bail in October but is unable to leave Iran. She now faces charges of her own, Rezaian’s family said, but those charges appear to be less severe than those levied against her husband.

Mary Rezaian, who resides in Istanbul, traveled to Iran in December and was granted permission to visit her son twice at the end of last month. During the first visit, which took place on Dec. 25, she was accompanied by Salehi’s mother. The two women met with Rezaian for about an hour. While they talked, a camera set on a tripod filmed the meeting.

Mary Rezaian said she was taken aback by her son’s appearance. “He looked very different,” she said. “He had lost 40 pounds.”

In a second visit on Dec. 30, both his mother and Salehi were permitted to speak with Rezaian separately, but only for a short while. It was the first time that Salehi had been permitted to see or talk to her husband since early December.

Mary Rezaian said her son has struggled to obtain adequate treatment for several health problems. Prison officials are providing medication for chronic high blood pressure, but Rezaian, 38, went weeks without treatment for an eye infection. He has also suffered from back problems resulting from sleeping on the floor and at times has been unable to walk normally.

Rezaian also appears to be struggling to keep his spirits up, his mother said. “Jason is normally a very sunny, bubbly person,” she said. “I would say that he is depressed and very frustrated.”

While Rezaian was previously held in solitary confinement, he is now kept in a cell with another prisoner, his family said. He is given access to fresh air and exercise on a regular basis. Initially, he was subjected to extensive interrogations five to six days a week, but he has not been interrogated for some time.

Ali Rezaian said the lengthy interrogation reflected the weaknesses of the case against his brother. The government “has been trying to generate proof of something, of anything,” he said.

Iranian officials have not allowed Rezaian to speak to a lawyer his family has hired in Tehran. Nor has the lawyer been able to obtain information about the charges against Rezaian.

His case is now expected to be referred to Iranian court for trial, but it is unclear when that will occur.