WASHINGTON - The family of a former FBI agent who vanished in Iran in 2007 has released a hostage video showing him alive and asking for help.The video shows Robert Levinson, looking gaunt, asking for the US government's help "to answer the requests of the group that has held me for 3-1/2 years." He does not identify the group in the footage, posted on a website dedicated to his release.RELATED:US 'hikers' leave Iranian jail, head to airport Levinson's son and wife on Friday also posted a video message on the website, asking his captors to tell them their demands for his release.In March, US Secretary of State Hillary Clinton said the United States had indications that Levinson was being held in southwest Asia, and appealed to Iran to provide information about him.Levinson said in the video he was being treated well but added: "I am not in very good health. I am running very quickly out of diabetes medicine."In the family's response, one of Levinson's sons, David, said the video "was a comfort to the family because it shows us that my father is alive and that he looks healthy.""My mother has received your messages," he says. "Please tell us your demands so we can work together to bring my father home safely. Thank you for taking care of my father and for continuing to provide him with the care and medical treatment he needs to stay alive." Levinson disappeared while on a business trip to Iran's Kish island.