PHOTO: Boko Haram leader Abubakar Shekau and Islamic State leader Abu Bakr al-Baghdadi

Nigeria’s insurgency Boko Haram may have pledged allegiance to the Islamic State, in an audio recording circulated on Saturday.

The pledge was attributed to Boko Haram leader Abubakar Shekau on Boko Haram’s Twitter page: “We announce our allegiance to the Caliph [Islamic State leader Abu Bakr al-Baghdadi]…and will hear and obey in times of difficulty and prosperity.”

Simon Copeland, a specialist on Boko Haram at the University of Birmingham, assessed on Sunday, “Although it’s not been verified, most of the people who are in the know seem to think the statement is from the top of Boko Haram, likely Shekau — he has also made statements seeming to court the Islamic State in the past.

See EA Audio Analysis: Have Boko Haram and Islamic State Established an Alliance? (No.)

Boko Haram, which has been battling the Nigerian Government since 2009, controls widespread portions of northeast Nigeria. Violence has escalated in recent months, with other African countries carrying out cross-border operations in an attempt to quell the insurgents.

While Boko Haram leader Shekau has made general statements of support to the Islamic State, claims of an operational alliance between the two groups have been speculative.

On Saturday, three bombs killed more than 50 people and wounded scores of others in Maiduguri, in the worst attacks there since Boko Haram fighters tried to seize the northeastern city in two assaults earlier this year.