Jailed Washington Post reporter Jason Rezaian should know the verdict in his trial for spying on Iran "within a week", his lawyer told AFP after court proceedings ended Monday.

The 39-year-old Iranian-American journalist has been in custody for more than a year and his trial has been held behind closed doors.

Rezaian's family and employer have denounced the accusations of espionage as a sham.

Outside court his mother said the reporter, who has suffered bad health because of his incarceration, was "paying the price" of historically bad political relations.

Confirming that Monday's hearing was the last in the case unless there is an appeal, the reporter's lawyer Leila Ahsan said she had presented her defence and a judgment would follow.

"The verdict will be issued and communicated to us within a week," she told AFP by telephone in Tehran.

"I expect my client to be acquitted as he is innocent."

The latest hearing -- the fourth -- was the first since Iran struck a nuclear deal with the United States and other world powers.

Iran and the US have said there is no linkage between the charges against Rezaian and nuclear talks but American officials and lawmakers have called for the reporter's release.

Ahsan on July 28 said she hoped the accord -- in which Iran agreed to curb its nuclear programme in return for the lifting of crippling sanctions imposed by the West -- would hasten her client's release.

Rezaian's trial, on charges of "espionage, collaboration with hostile governments, gathering classified information and disseminating propaganda against the Islamic republic," started in May.

- 'Paying the price' -

The case has been heard by a Revolutionary Court, which usually presides over political cases or those related to national security.

Rezaian, the Post's Tehran correspondent, was arrested with his wife Yeganeh Salehi, also a journalist, at their home in Tehran on July 22, 2014.

Salehi and a photographer who was arrested on the same day were released on bail after two and a half months in custody.

Rezaian's wife has not worked since and she is barred from discussing the case but Ahsan said that she expected court action against the other accused.

"The verdict for Mr Jason Rezaian will be delivered and her (Salehi's) trial and the third person's will be later," Ahsan said, though it is not known what charges either would face.

Salehi and Rezaian's mother Mary were at court but not allowed inside.

"This case is not about what Jason did. This is a political case, political issues between the United States and Iran," the reporter's mother said.

"Jason is a dual citizen and he is paying the price of the suspicion, the animosity, and the paranoia between the two countries."

She added: "Jason's rights as an Iranian citizen have not been fulfilled because he was kept in prison more than one year and many times his trial was delayed. I'm challenging those people who arrested him and are trying him, to show the evidence" accusing him of espionage.

Washington Post executive editor Martin Baron on Saturday criticised Rezaian's trial and the conditions of his incarceration.

"Iran has behaved unconscionably throughout this travesty of a case," he said.

"It has imprisoned an innocent journalist for more than a year and subjected him to physical mistreatment and psychological abuse.

"The secret court proceedings that began on May 25 have been a farce."

Requests that Rezaian be released on bail have been refused.