BAGHDAD — A previously unknown Shiite militia released a video Friday that shows more than a dozen Turkish construction workers who were kidnapped in Baghdad recently and demands that Turkey stop the flow of jihadists into Iraq and lift a siege of several Shiite-dominated villages in Syria.

If its demands — issued in writing, in Arabic, at the end of the video — are not met, the group vowed that it would “strike the interests of Turkey and its agents in Iraq with the most violent means.”

Many Shiite militias operate in Iraq, many with the backing of Iran, but the group that purported to release the video Friday had not previously been heard of. It called itself “Death Squads” and referred to Imam Hussein, a grandson of the Prophet Muhammad revered by Shiites as a martyr whose death in 680 at the hands of Sunnis was the beginning of the sectarian divide within Islam.

The abduction of the workers — a Turkish official has said that 17 Turks and their Iraqi Kurdish translator were taken — occurred in the early morning hours of Sept. 2 at a construction site in Sadr City, a vast Shiite neighborhood in Baghdad. The workers were building a large soccer stadium. Since then Iraqi security officials have been investigating, and a recent shootout in Baghdad between the security forces and militiamen was said to have stemmed from that investigation.