The brother of a Washington Post reporter detained in Iran since July 2014 delivered a petition to Iran's United Nations mission on Thursday demanding the journalist's release.

"They need to know that folks around the world are concerned about this," Ali Rezaian said before handing over the petition seeking the release of his brother Jason Rezaian.

Thursday marked 500 days since Jason Rezaian's arrest on July 22, 2014. Rezaian was detained with his wife, Yeganeh Salehi, and two photojournalists. The others were released, but Rezaian went on trial in four closed-door court hearings at Tehran's Revolutionary Court.

Iranian state TV reported last month that Rezaian had been sentenced to an unspecified prison term following his conviction on charges that include espionage.

The 39-year-old Rezaian has dual American and Iranian citizenship. The Washington Post and his family say he had no involvement in spying.

The U.S. State Department said it supports the petition demanding Rezaian's release and is continuing its own efforts to free him.

"Jason should have been free these last 500 days to pursue stories close to his heart, stories that promote understanding of Iran's people," department spokesman Mark Toner said in Washington.

Toner said Rezaian's "continued detention remains an injustice."

Also on Thursday, the publisher of The Washington Post said the United States, other governments and businesses should keep Rezaian in mind when considering improved relations with Iran.

Publisher Frederick J. Ryan Jr. said in a statement that "if the callous regime in Tehran imprisons and abuses a fully accredited and innocent journalist, what might they do to a visiting delegation?" He also wondered "how would they treat employees stationed in Iran?"

The Post said Wednesday that it has submitted new information about Rezaian to a U.N. working group on arbitrary detention. Earlier this year, it appealed to the group to intervene in the case.

The new filing with the group details the lack of openness in his case and calls the legal proceedings "farcical." His lawyer, Leila Ahsan, told The Associated Press she had not been informed of the verdict, let alone details of the sentence.

His brother said Rezaian's family is worried about his health deteriorating.

"There's no excuse for holding Jason," said Ali Rezaian, 44, of Mill Valley, California. "He's innocent. He's been innocent from the beginning and they know that but they haven't released him."

Ali Rezaian delivered the petition — containing 533,000 signatures from people around the world — on a thumb drive. He spent about five minutes at the Iranian mission and then was escorted out.

Officials with the mission did not immediately return phone calls seeking comment.

U.N. human rights experts last month called for Rezaian to be released, and the U.S.-based Committee to Protect Journalists has demanded the same. Last month, the CPJ said 30 journalists were behind bars in Iran in 2014, more than in any other country except China.