The ISIS revealed the information by releasing a video.

IS said it was part of its recently declared campaign to "avenge" the death of its leader Abu Bakr al-Baghdadi during a US raid in Syria in October, reported BBC.

No details were given about the victims, who were all male, but IS says they were "captured in the past weeks" in Nigeria's north-eastern Borno State, reported the British news website.

The video was unveiled on Dec 26.

Incidentally, the video has been released at a time when the country was celebrating X-mas festival.