Islamic State West African Province (ISWAP) said in an audio recording obtained by Reuters on Sunday that Abubakar Shekau, leader of rival Nigerian militant Islamist group Boko Haram, was dead.

Shekau died around May 18 after detonating an explosive device when he was pursued by ISWAP fighters following a battle, a person purporting to be ISWAP leader Abu Musab al-Barnawi said on the audio recording.

Two people familiar with al-Barnawi told Reuters the voice on the recording was that of the ISWAP leader.