BBC reports that the Islamist group IS has a new faction of Boko Haram which now fights under the name of "Islamic State West Africa Province"
The Islamic State group released a video claiming to show the killing of 11 Christians in Nigeria.
IS said it was part of its recently declared campaign to "avenge" the October deaths of its leader and spokesman in Syria.
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.
The 56-second video was produced by IS's "news agency" Amaq.
It was released on 26 December and analysts say it was clearly timed to coincide with Christmas celebrations.
The footage was filmed in an unidentified outdoor area.
One captive in the middle is shot dead while the other 10 are pushed to the ground and beheaded.
IS's late leader and spokesman Abu Bakr al-Baghdadi and Abul-Hasan Al-Muhajir were killed in Syria in late October. Nearly two months later, on 22 December, IS declared a new militant campaign to "avenge" their deaths and has since claimed a flurry of attacks in various countries under the banner of that campaign.
Source: Edited from BBC News