BEIRUT (AP) -- The spokesman for Islamic State militants said Thursday that the extremist group has accepted the pledge of allegiance by West Africa's Boko Haram group.
In an audio recording released by the group's media arm Al-Furqan, Abu Mohammed al-Adnani claimed the pledge of allegiance meant that the caliphate has now expanded to West Africa.
The recording was released a few days after an audio recording from Boko Haram leader Abubakar Sheka posted online Saturday in which he pledged allegiance to IS.
Al-Adnani also urged foreign fighters from around the world to migrate and join Boko Haram.
Boko Haram killed an estimated 10,000 people last year, and it is blamed for last April's abduction of more than 275 schoolgirls.
In August, Boko Haram followed the lead of IS in declaring an Islamic caliphate in northeast Nigeria that grew to cover an area the size of Belgium. The Islamic State had declared a caliphate in vast swaths of territory that it controls in Iraq and Syria.
Boko Haram is waging a nearly 6-year insurgency to impose Muslim Shariah law in Nigeria. It began launching attacks across the border into Cameroon earlier this year, and then struck in Niger and Chad.
Members of the U.N. Security Council proposed Thursday that the international community supply money, equipment, troops and intelligence to a five-nation African force fighting Boko Haram.