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

Ali Rezaian (AH'-lee reh-ZY'-ihn) on Thursday delivered the petition signed by 533,000 people worldwide.

Thursday marked 500 days since Jason Rezaian's arrest. 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 Washington Post and Rezaian's family have denied that Rezaian had any involvement in spying.

His brother, of Mill Valley, California, says there's "no excuse for holding Jason."

Ali Rezaian delivered the petition on a thumb drive and spent about five minutes at the Iranian mission's office. He then was escorted out.