GUANTANAMO BAY NAVY BASE, Cuba — An Islamic opposition group in Syria has posted a video of the funeral of a former Guantanamo prisoner, the first known report that one of the 500 or so captives released during the Bush administration joined the Syrian insurgency to topple Bashar Assad.

The Syrian Islamic Movement posted the video Monday on YouTube. It shows the body of a fallen fighter in his 30s or 40s and a rebel leader, Sheik Abu Ahmad al Muhajir, eulogizing the man as Mohammed al Alami, a Northwest African veteran of the jihad in Afghanistan "who went through hardship for the sake of God in the prison of the Americans in Guantanamo for five years."

U.S. Defense Department officials who help track released Guantanamo detainees had no comment Tuesday.

Aaron Zelin, editor of the jihadology blog from the Washington Institute for Near East Policy, said the posting from the Aug. 5 funeral confirmed reports of a former Guantanamo prisoner's death in Syria that had been floating around the Internet for weeks.