Nigerian Defence Minister Mohammed Badaru Abubakar has resigned, as the country grapples with a surge in mass kidnappings that prompted President Bola Tinubu to declare a national security emergency.

Presidential spokesman Bayu Onanga said on Monday that the 63-year-old Abubakar stepped down with immediate effect for health reasons. He added that the resignation coincides with the president’s emergency declaration, with plans to clarify its scope in due course.

Kidnappings for ransom by armed groups have become increasingly frequent in Nigeria since the 2014 abduction of 276 schoolgirls in Chibok, northeastern Nigeria, by the extremist group Boko Haram.