A suspected suicide bomber has blown himself up inside a mosque in Nigeria's Maiduguri city killing 10 people, a hospital source said, after an attack by Boko Haram insurgents on the outskirts.
The attacks occurred a day after the inauguration of President Muhammadu Buhari, who swore to crush the Islamist militant group and move the command centre for military operations away from the capital Abuja to Maiduguri.
"A male bomber suspected to be Boko Haram is said to have entered a mosque near the (Monday) Market to detonate," a military source said.
A military source said the early morning shooting took place around the Damboa road near the small settlement of Mule, about 10 km (6 miles) from Maiduguri, a city of two million people.
"A rocket launcher from Boko Haram hit a house around the Bulumkutu area...and killed five people. Our boys also picked up six corpses in different locations," local militia member Mohammed Bunu said.
The militants tried to cross trenches dug around the city, he said.
These attacks follow twin bomb blasts early on Friday in Tashan Alade, a remote Borno town, which killed at least seven people.
Thousands have been killed and about 1.5 million displaced during Boko Haram's six-year-old insurgency to carve out a state adhering to strict Islamic law in Nigeria, Africa's biggest economy and top oil producer. At the start of the year, it controlled a swathe of territory larger than Belgium in the northeast of the country.
Boko Haram has since been pushed back with the help of offensives launched by troops from Chad and Niger while Cameroon has fought them off along its borders.
As feared, the group is showing a return to its guerrilla tactics since losing the territory it gained last year. It maintains a last stronghold in the Sambisa forest reserve.
"They may resort to more spectacular brutality against soft targets to maintain relevance as Al Shabaab has in Kenya," a western diplomat in the capital Abuja said.
The United States and Britain said on Friday they were ready to increase military cooperation with Nigeria to defeat Boko Haram.