BAGHDAD — The leader of the “Islamic State” has accepted a pledge of allegiance from Nigerian Islamists Boko Haram, his spokesman said, calling on supporters to fight in Africa.

Boko Haram, which has killed thousands and kidnapped hundreds during a six-year campaign to carve out an Islamist state in northern Nigeria, pledged its allegiance last week, highlighting increased coordination between jihadi movements across north Africa and the Middle East.

“Our caliph, God save him, has accepted the pledge of loyalty of our brothers of Boko Haram, so we congratulate Muslims and our jihadi brothers in West Africa,” IS spokesman Abu Mohammad al-Adnani said in an audio message, referring to his group’s leader Abu Bakr al-Baghdadi.

Adnani called on Muslims who could not join IS in Iraq and Syria to enter combat in Africa instead, saying Boko Haram’s pledge had opened a “new door for you to migrate to the land of Islam and fight.”

“We are calling you up for jihadis, go.”