A Swedish court has sentenced a Syrian man to life imprisonment for participation in the 2012 mass execution of seven government troops in Syria.

The Stockholm District Court ruled that 46-year-old asylum-seeker Haisam Omar Sakhanh joined the armed group Suleiman Company in early May 2012, and shot a person dead with an assault rifle.

In its Thursday ruling, the court said Sakhanh said he had been ordered to do so by a superior, which the court rejected.

Judge Tomas Zander said the victim, who was not identified, was shot dead along with six others "under particularly cruel circumstances."

Sakhanh had sought asylum in Sweden in 2013 and has been held in pre-trial custody since March.