DAMASCUS– A former prisoner at the Guantanamo Bay U.S. naval base died fighting for anti-government rebels in Syria, according to an Islamist opposition group which posted a video of his funeral on YouTube.

Moroccan-born Mohammed al Alami, who was released in 2006, is the first former Guantanamo detainee to die in battle in the Syrian civil war, analysts say.

The video, first reported by The Miami Herald, was posted by Harakat Sham al-Islam, one of the Islamist brigades fighting against Syrian President Bashar al-Assad. It showed the August 5 funeral in which Alami is praised by a rebel leader for enduring “the prison of the Americans in Guantanamo for five years … where he did not reform or change.”

U.S. Defense Department officials had no comment.

Aaron Zelin, a fellow at the Washington Institute for Near East Policy said the video appeared to confirm rumors that had been circulating for several weeks about a former Guantanamo prisoner being killed in Syria.

“The sources seem to be legitimate,” he said, adding that the video was posted on a known jihadi website.

Last month the U.S. repatriated two Guantanamo detainees to Algeria as part of its ongoing effort to close the prison.

So far, the U.S. has released 606 detainees. There are currently 164 prisoners at Guantanamo, including 84 cleared for release years ago.