Police in Nigeria have been put on red alert and may seek the help of the military after protests turned violent in some cities, leaving at least three people dead, the inspector general of police said.

Some major cities, including the capital Abuja and Kano in the north, which on Thursday witnessed clashes between police and demonstrators and looting, appeared calm early on Friday as protests were expected to continue.

Kayode Egbetokun said late on Thursday that police had fully mobilised and were prepared to respond swiftly to any further threats to public safety and order.

"In the light of the current situation, the Nigeria Police Force has placed all units on red alert," Egbetokun said.

"The Police is equipped to respond appropriately to the unfolding situation and will get assistance from other security agencies, including the military if the need arises."

Inspired by youth-led protests in Kenya, Nigerians organised the "#EndBadGovernanceInNigeria" protests online, saying they would sustain their action for 10 days.

Protesters have been angered by President Bola Tinubu's economic reforms that have caused rampant inflation, weakened the currency and inflicted increasing hardship on ordinary Nigerians.

Tinubu says that while he understands the pain caused by the reforms, they are the only way to put Nigeria's economy on a firm path to economic growth.

Kano, a largely Muslim state and among the most populous in Nigeria, imposed a 24-hour curfew after protesters looted a shop and a government complex, while three other states also imposed curfews in some areas.