The video shows three armed wearing fatigues in a room with Mohammed Kanaan, a military officer who had registered to run in June 3 elections.

In a video filmed by the militants brigade and distributed online by militants’ media activists, he is shown wearing a suit, seated on an armchair.

"The Tabarak al-Rahman Brigade has arrested one of the presidential candidates," said an unnamed militant seated next to Kanaan.

Prompted to speak, Kanaan says he is a colonel in the army's First Division tank battalion, and that he was stopped by a militant from the so-called Free Syrian Army while travelling from Damascus to Daraa.

Tens of thousands of people have gone missing over the course of Syria's conflict.

The militant groups use them for threatening Syrian government or for punishing people who don’t obey them.

Other motivations for abductions include extortion and hostage exchange, eradicating criticism, eliminating political rivals.

Countless videos of executions by militant groups have been circulating over the internet, while many other crimes remain unreported.

Syria sank into war in March 2011 when pro-reform protests turned into a massive insurgency following the intervention of Western and regional states.

The unrest, which took in terrorist groups from across Europe, the Middle East and North Africa, has transpired as one of the bloodiest conflicts in recent history.

SHI/SHI