In recent weeks, fighting has been the fiercest in the northeast Nigerian town of Maiduguri, Borno, Nigerian Col. Ben Ahonotu told CNN Sunday.
Attacks on police and government targets also continued in Yobe, Kano and Katsina states, Ahonotu said.
The Islamic sect Boko Haram wants the government to impose Islamic law, known as Sharia, throughout the Muslim-dominated northern half of Nigeria. The southern half of the country is predominantly Christian.
Boko Haram leader Mohammed Yusuf was reported captured by the military Thursday and died in police custody.
Human rights groups are seeking more information about his death and the civilian casualties, CNN reported.