Sixteen people were killed on Wednesday when a bomb blew up a village cafe in Nigeria's Borno state, hotbed of the Boko Haram militant insurgency, police said.

No group has claimed responsibility for the attack, which also injured several people.

Police spokesperson Nahum Kenneth Daso said on Thursday the government had imposed a 24-hour curfew following the attack, which came barely a week after a landmine explosion on a highway in Borno state killed seven soldiers.

Local resident Kachallah Goni told Reuters he heard a loud explosion at around 1930 GMT on Wednesday at a popular cafe in Kawuri village, a few kilometres from Maiduguri, the capital of Borno state.

Mustapha Modu, a local vigilante, said he recovered at least 20 bodies from the cafe.

Nigeria faces a series of security challenges including a long-running Islamist insurgency in the northeast, separatist violence in the southeast, rampant oil theft in the Niger Delta and kidnapping for ransom by criminal gangs.

On Thursday, thousands protested in cities across Nigeria against widespread insecurity, the rising cost of living, and governance issues.