Story highlights A British official says authorities are assessing the video

British journalist John Cantlie is in a video released by ISIS

He says he was abducted by the group in November 2012

Cantlie was kidnapped with U.S. journalist James Foley

British journalist John Cantlie hadn't been seen in nearly two years. Now, he's the latest hostage to be paraded out by ISIS -- forced to deliver the group's message.

In a video released Thursday, Cantlie -- wearing an orange shirt and seated alone at a desk with a black backdrop -- says he is sending what will be the first in a series of messages on behalf of the group that calls itself the Islamic State.

Since Cantlie is delivering ISIS propaganda and makes clear in the video he is speaking under duress, CNN is not showing the video on its platforms.

In recent weeks, ISIS has drawn growing attention for spewing brutal propaganda across social media -- messages meant both to terrify and recruit Westerners. The group appears to have a well-funded, well-organized social media and video production effort. Its videos are slickly produced, with high production values.

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Cantlie, a photojournalist who also wrote several articles for major British newspapers, was kidnapped in November 2012 along with American journalist James Foley

Cantlie's LinkedIn profile describes him as a journalist and photographer with 20 years' experience specializing in working in hostile environments, including Afghanistan, Somalia, Libya and Syria.

"I love stories of ordinary people in extraordinary circumstances," he wrote in an online portfolio describing his work.

He was previously abducted in Syria with a Dutch journalist in July 2012. Both were shot when they tried to escape through a hole in their tent.

"We stepped out the back and ran for our lives," he said in a television interview describing the failed escape attempt.

Several days later, they were rescued by Free Syrian Army rebels.

On his return, Cantlie reported that some of the hostage-takers were British, including a London-based doctor who treated his gunshot wounds.

In London's Sunday Times, he described his experience being held at a camp in Syria.

The British citizens there were seemingly of mixed ethnicities and spoke of a wider war after Syria "because when they learn that Sharia (law) is spreading into Syria, then we will be at war with America," Cantlie told the Times

Just a few months later, Cantlie returned to Syria, only to be kidnapped again. In the video, he says he was captured by the Islamic State after he returned to Syria in November 2012.

Now, ISIS is using him, as a journalist, as a British hostage, forcing him to deliver their message.

In the video, Cantlie says he will be telling the story of the other side of ISIS.

"You're thinking, 'He's only doing this because he's a prisoner. He's got a gun at his head, and he's being forced to do this.' Right? Well, it's true. I am a prisoner. That I cannot deny," Cantlie says in the video. "But seeing as I've been abandoned by my government and my fate now lies in the hands of the Islamic State, I have nothing to lose."

Contacted by CNN about the video, a British official said the Foreign & Commonwealth Office is assessing the production, considering its implications and trying to contact Cantlie's family.