The trial in Iran of jailed Washington Post reporter Jason Rezaian will be closed to the public when it starts on Tuesday, his brother said on Monday.Rezaian, who is Iranian-American and faces unspecified charges, will be in Revolutionary Court with only his attorney and family members are excluded, his brother Ali Rezaian told Reuters Television.Jason Rezaian, the Post's Tehran bureau chief, has been in Tehran's Evin prison since his arrest in July. Iran has not elaborated on the charges, but the Post has said he was charged with espionage."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 said."It's unlike the Iranian court system, Iranian government, to keep things private when they can go out and use propaganda up against people."Ali Rezaian said the family had hoped that Rezaian's wife, journalist Yeganeh Salehi, and his mother would be allowed to attend the trial. He said his brother had lost 40 pounds (18 kg) in prison.Rezaian, who is from Marin County, California, was arrested at his home in Tehran alongside his wife and two Iranian-American friends who have not been named. Salehi was freed on bail while the couple were released. The three have not been publicly charged.Citing his lawyer, the 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."Douglas Jehl, the Post's foreign editor, called the charges baseless. "What Jason did was act as a journalist, which involves gathering information, verifying information, and ultimately publishing it," he told Reuters Television.A spokesman for the Iranian special interests section in Washington, which acts as Tehran's embassy, could not be reached for comment.US President Barack Obama has called the charges against Rezaian "vague" and pressed Iran to release all American detainees.Tehran and six major world powers, including the United States, are trying to meet a June 30 deadline for a final nuclear deal to end a decade-old standoff with the West.Iranian Foreign Minister Mohammad Javad Zarif said in April that an intelligence operative, possibly linked to the US government, may have "taken advantage" of Rezaian.