Niger's defense minister says that four officers arrested in December have confessed to planning an attempt to overthrow the government.

National Defense Minister Mahamadou Karidjo said Wednesday that Gen. Souleymane Salou, the former chief of staff, was the mastermind among the four who confessed. He said Niger's authorities arrested 12 soldiers and 11 civilians on accusations of planning an overthrow of the government in December.

Niger President Mahamadou Issoufou at that time warned a political vacuum could lead to more instability by Islamic extremists. Niger has seen extremist attacks for years, most recently by Nigeria's Boko Haram.

Niger, which has a history of military strongmen seizing power by force, is scheduled to hold national elections on Feb. 21.