Authorities on Sunday relaxed a 24-hour curfew slapped on Kano, Nigeria's second largest city after coordinated bombings and shootouts killed at least 162 people.

The curfew was imposed on Kano in Nigeria's mainly Muslim north after it exploded in violence on Friday evening, with eight police and immigration offices or residences targeted.

"Following the return of relative calm in the city, the government hereby relaxes the 24 hour curfew," Faruk Jubril, Kano state government spokesman said.

Curfew times will now be from dusk-to-dawn.

Rescue workers spent Saturday picking up bodies that littered the streets following the attacks that came after Muslim Friday prayers.

A purported spokesman for Islamist group Boko Haram had claimed responsibility for the violence, saying it was in response to authorities' refusal to release its members from custody.

Scores of such attacks in Nigeria's north have been blamed on Boko Haram, though Friday's would be among the group's most audacious and well-coordinated assaults.

Some 20 huge blasts went off in the city targeting a number of police offices including a police headquarters, a secret police building and immigration offices.

The attacks in Kano, which had escaped the worst of the violence blamed on Boko Haram in recent months, sent residents fleeing in fear of what would come next.