Video released on website yesterday shows Robert Levinson's pleas for help.
Former FBI agent's plea from Iran
The family of a former FBI agent, who vanished on Iran's Kish Island four years ago after travelling from Dubai, have released a video of him pleading for help to get home.
Robert Levinson flew from Dubai to Kish Island, an Iranian free zone, in 2007 to look into a possible cigarette-smuggling ring. He has not been seen since.
The video, released yesterday, shows him held hostage by "unknown kidnappers" and looking very thin, according to Agence France-Presse.
"I have been treated well but I need the help of the United States government to answer the requests of the group that has held me," Mr Levinson said.
"I am not in very good health. I am running very quickly out of diabetes medication."
Mr Levinson goes on to say "please help me get home". It was not clear when the video was made or where it was filmed.
His family released the footage on their website, helpboblevinson.com, along with a video of his wife and son.
"Please tell us what you want and please bring my father home," said David, his son. Mr Levinson's wife, Christine, said they would not abandon him.
Mrs Levinson last saw her husband on March 8, 2007, before he left for Dubai.
The last public sighting of him was the next day, on the eve of his 59th birthday, getting into a taxi bound for Kish airport.
In March this year Hillary Clinton, the US secretary of state, appealed to Iranian authorities to release Mr Levinson so he could be reunited with his family.
"We would appreciate the Iranian government's efforts in this matter," Mrs Clinton said in a statement.