The head of the secret police in the northern Nigerian city of Kano, ravaged by violence claimed by the Islamist Boko Haram group, said Wednesday its members wore police uniforms to launch attacks.

"The sect members disguise as policemen... to launch attacks on police personnel and make it look like policemen are sent to kill their colleagues," Bassey Eteng told journalists.

Eteng showed reporters three police uniforms, three forged police ID cards, 11 police rifles and boots allegedly recovered on Monday in an army raid on a Boko Haram hideout in which eight suspected sect members died.

Home-made bombs, ammunition, bomb-making tools and guerilla warfare manuals in the local Hausa language were also recovered and displayed to reporters.

Boko Haram members took police uniforms and rifles in raids on the police headquarters in the northeastern Yobe state last November.

They launched multiple suicide and bomb attacks in the state capital Damaturu killing 150 people, Eteng said.

The state security service Wednesday arranged a tour of the suspected sect hideout raided in Kano's Mariri neighbourhood for select journalists under military escort.

Residents said they were accustomed to seeing people in police uniform in the neighbourhood who they thought were genuine policemen.

Boko Haram's insurgency has included both small and large-scale attacks, which have mainly targeted the police and other symbols of authority.

The group has claimed assaults that have killed more than 200 people already this year, including a sophisticated series of gun and bomb attacks in Kano on January 20 that claimed at least 185 lives -- its deadliest attack yet.