James Lawler Duggan / AFP - Getty Images, file

Freelance photographer Austin Tice, seen in this July 2012 picture taken at an undisclosed location, has been missing since Aug. 13.

The U.S. believes missing American journalist Austin Tice is in the hands of the Syrian government, a State Department spokeswoman said, after a YouTube emerged purporting to show him at the hands of his captors.

Spokeswoman Victoria Nuland told reporters Monday that the State Department was unable to verify the accuracy of the video, which appears to shows Tice with masked men that one expert described as a "caricature of a jihadi group."

Nuland said that the video “may have been staged” and added, “There’s a lot of reason for the Syrian Government to duck responsibility, but we continue to believe that, to the best of our knowledge, we think he is in Syrian Government custody."

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Former U.S. Marine Tice, who worked for outlets including The Washington Post and media group McClatchy Newspapers, has been missing in Syria since Aug. 13.

He posted on Twitter on Aug. 11 saying he had been celebrating his birthday with Syrian rebels.

McClatchy reported on its website Monday that Tice was “alive and in the custody of armed men” and quoted Tice’s parents, Marc and Debra, as saying the video was “reassuring.”

It quoted a statement from the Houston couple saying:

“Though it is difficult to see our son in such a setting and situation as that depicted in the video, it is reassuring that he appears to be unharmed. It is evident that the current events in Syria are challenging and difficult for everyone involved. Our wish is that peace and stability can once again return to the people of Syria and that our eldest son, Austin, will soon be safely returned to our family.”

The video clip, which shows masked men carrying guns, came to light after it was shared on a Facebook page associated with supporters of the government of Syrian President Bashar Assad.

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NBC News could not confirm the authenticity of the video. The New York Times reported that several analysts expressed doubts about the authenticity of the video.

The Washington Post also quoted Joseph Holliday, of the Washington-based Institute for the Study of War, as saying the video did not ring true and that the "captors" appeared to be wearing Afghan-style clothing rather than those normally associated with Islamists in Syria.

“It’s like a caricature of a jihadi group,” he told the newspaper. “It looks like someone went to the Internet, watched pictures of Afghan mujaheddin, then copied them. My gut instinct is that regime security guys dressed up like a bunch of wahoos and dragged him around and released the video to scare the U.S. and others about the danger of al-Qaida extremists in Syria. It would fit their narrative perfectly.”

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