"Zana Nusrat Abdel Karim, the chief of a cell of Ansar al-Islam and 11 other members were condemned to death by the criminal court of Arbil," an official told AFP.
The 12 were convicted of numerous "terrorist" activities and killings of civilians in Kurdistan's Arbil and Dahuk regions, the official said.
Karim, 35, a mechanical engineer and resident of Arbil used to carry out the killings of civilians at his home, the official added.
Another accused, Karzan Ismail Shamlah, was sentenced to life imprisonment as the prosecution was unable to prove his direct role in the crimes.
The official said the sentences were passed under Iraqi law and not just Kurdistan law. On July 13, 2005, the Kurdistan Democratic Party-run television had aired confessions of the accused.
"We used to attract people to my house and then slit their throats. The killings were part of training to the group members on how to kill people," Abdel Karim, the chief of the cell, was shown as saying in the video footage.
He said the bodies of the victims were cut in pieces and "put in plastic bags and later dumped." The footage also showed such a training scene, where a victim's throat was slit.