According to an audio statement, Boko Haram has pledged allegiance to Islamic State (ISIS).
The message, which has not be verified, was posted on the Nigerian militant group’s Twitter account and appeared to be by Boko Haram’s leader Abubakar Shekau.
Boko Haram began a military campaign to impose Islamic rule in northern Nigeria in 2009. The conflict has since spread to neighboring states.
It would be the latest in a series of groups to swear allegiance to ISIS.
Boko Haram’s insurgency has threatened Nigeria’s territorial integrity and triggered a humanitarian crisis.
The militant group has carried out frequent bombings that have left thousands dead and has also attacked targets in the capital, Abuja.
ISIS has forged links with other militant groups across North Africa and the Arabian Peninsula.
In November 2014, ISIS leader Abu-Bakr al-Baghdadi accepted pledges of allegiance from jihadists in Egypt, Libya, Algeria, Yemen and Saudi Arabia.
In January 2015, militants in Afghanistan and Pakistan announced that they were forming an ISIS province.