Media reports suggest that 39-year-old Danish citizen Slimane Hadj Abderrahmane has been killed in combat in Syria.

Abderrahmane, born to a Danish mother and Algerian father, is known for the two years he spent in American custody at the Guantanamo military base after being captured in Afghanistan in 2001.

“Slimane was a man who could not stand to see Muslims suppressed, so a few months ago he travelled to Syria to once again perform Jihad and do his duty to fight Allah’s enemies,” the Facebook group Islamisk Budskab wrote on Sunday. “He packed his rucksack, said goodbye to his wife and children, headed to Copenhagen Airport and flew onward toward the war in Syria.”

Despite repeated reports, the Danish domestic intelligence agency PET could not confirm whether Abderrahmane had been killed.

“PET cannot confirm with any certainty that the Danish citizen Slimane Hadj Abderrahmane was killed due to fighting in Syria,” PET wrote according to state broadcaster DR.

Politiken newspaper reported, however, that Abderrahmane and another Danish citizen were killed on Saturday.

Abderrahmane held at the Guantanamo base in Cuba for two years before being released to Denmark in 2004 after American authorities chose not to prosecute him.

In 2007, while working as a postman in the Copenhagen suburb of Greve, Abderrahmane was convicted of stealing credit cards and withdrawing 110,000 kroner. He spent ten months in jail but most of the money was never recovered.

In 2011, he sued the Danish government for not preventing his two-year detention in Cuba.

In an interview with Politiken newspaper the same year, Abderrahmane said he was not afraid to die fighting for Islam.

“Jihad means serving God and by doing so you achieve justice,” he said.

Abderrahmane was born in Roskilde and at the age of seven moved to Algeria, where his grandmother helped form his Islamic faith.

According to PET, Abderrahmane is part of a growing number of Danes who have gone to Syria to fight against Bashar al-Assad's regime. One source within the Danish Muslim environment told Politiken that he   knew of at least 30 Danes who had travelled to Syria to take part in the war. PET, however, did not put a number on how many Danes may have gone to Syria.