BERLIN -- A Syrian man charged with war crimes for allegedly participating in the 2013 kidnapping of a United Nations observer -- believed to be a Canadian lawyer -- has gone on trial in Germany.

The 25-year-old, who came to Germany as a refugee in 2014, is accused of helping guard the observer for the Nusra Front, al-Qaida's branch in Syria.

The suspect has been identified only as Suliman Al-S. in line with German privacy rules.

Prosecutors haven't identified the observer but the facts released correspond with those of the kidnapping of Canadian lawyer Carl Campeau, who was abducted in the Damascus suburb of Khan Al-Sheik.

Campeau, who was working as a legal adviser for the UN Disengagement Observer Force, escaped after eight months.

The Montreal native told Syrian state television at the time that he escaped his captors when the gunmen neglected to lock the room where he was being held.

The accused Syrian's charges include war crimes, aggravated deprivation of liberty and membership in a foreign terrorist organization.

The trial opened Thursday at the Stuttgart state court and will last into next year.