ISLAMIC STATE has killed 11 hostages in Nigeria, the terrorist group has claimed.

Video footage of the apparent killings was released on Boxing Day, December 26, and experts have said its release date was chosen to clash with Christmas observances in order to attract optimum attention. Most of the beheaded are understood to be Christian.

In the 56-second video, members of ISIS say that the hostages, all of whom were male, were “captured in the past weeks” in Nigeria’s north-eastern Borno State, the BBC reported.

Further details of the victims, one who was shot dead, were not provided.

Nigerian publication The Guardian reported that journalist Ahmad Salkida said the executions were as an act of revenge in response to the killing of Abu Bakr al-Baghdadi.

Al-Baghdadi was killed in Syria during a US raid.

The BBC reported that president Muhammadu Buhari has condemned the apparent executions and warned against divisions along religious lines.

Attacks on civilians by Boko Haram and IS-linked groups have been stepped up recently, The Guardian Nigeria reported.

United Nations secretary-general António Guterres is deeply concerned about the reports that civilians have been executed.

A spokesman for the secretary-general said: “He expresses his deepest condolences to the families of the victims and reiterates the solidarity of the United Nations with the people and Government of Nigeria.”

“Those responsible for these atrocities must be held accountable. International human rights law and international humanitarian law must be fully respected, and all civilians in Nigeria must be protected,” he added.