'Please help me!' Video plea by former FBI man taken in Iran

Footage addressed to family highlights plight of Robert Levinson who went missing in 2007

Robert Levinson: Looking thin and unshaven, the captive reads from a prepared script in the video (AP)

The family of Robert Levinson, a private investigator who went missing in mysterious circumstances in Iran more than four years ago, has released a short video clip which suggests that he is alive and being held as a hostage.

In a minute-long filmed statement, which he said was addressed to his wife, children, grandson, and "the United States government", Mr Levinson, a 63-year-old former FBI agent, declared: "Please help me!"

"I am not in very good health," he revealed. "I am running very quickly out of diabetes medicine. 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, a father of seven, looks tired and is unshaven. He is sitting in front of a concrete wall, wearing a threadbare shirt. Despite showing no sign of recent physical mistreatment, he also appears to have lost a lot of weight.

The film was made late last year. It has been in the family's possession for some time, but until this week has remained under wraps so as not to complicate diplomatic efforts to bring him back home.

Its release yesterday suggests those efforts have temporarily stalled. Although it represents the last video communication they have received, the hostage's family were recently sent fresh sets of photographs which suggest that he remains alive.

Mr Levinson went missing in 2007 after travelling from Dubai to the Iranian island of Kish, a tourist resort in the Persian Gulf, to meet with a source. He had been in the region investigating cigarette smuggling operations for a private client.

Initially, the US wondered if Mr Levinson might have been either killed or arrested by Iranian authorities. But Tehran repeatedly denied any involvement in his disappearance and in a 2010 visit to the US, President Mahmoud Ahmadinejad offered to help American officials to track him down.

Because his statement refers to being held by a "group" rather than a government, the newly-released film adds weight to evidence that he is being held as a hostage. However, the US remains unsure about both who is holding him, and what country he might be in.

On the video, in which Levinson speaks to "my beautiful, my loving, my loyal wife, Christine", Pashtun music can be heard playing in the background.

Intelligence sources said that the video was accompanied by a demand for the release of several prisoners. However, the names on that list did not appear to match those of anyone the US is holding in custody.

Although it was sent from an internet address in Pakistan, the more recent photos were routed via a different address in Afghanistan, leading investigators to believe that Levinson's captors could be moving between the two countries.

His comments appear to be largely scripted. In an apparent reference to his former FBI service, Levinson ends the clip by saying: "Please help me get home. 33 years of service to the United States deserves something. Please help me!"

In a family statement accompanying the release, which was published on their website, the hostage's son, David, addressed the captors: "My mother has received your messages," he said. "Please tell us your demands so we can work together to bring my father home safely."

Meanwhile, his wife, Christine says: "Bob, I will continue to do everything that I can to bring you home alive. All I want is for our family to be whole again. We love you, we miss you every day. We will not abandon you."