A suicide bomber has blown himself up inside a mosque in Nigeria's Maiduguri city killing at least 16 people, local sources said, after a night-time attack blamed on Boko Haram fighters on the outskirts of the city.
The attacks on Saturday occurred a day after the inauguration of President Muhammadu Buhari, who swore to crush the armed group and move the command centre for military operations away from the capital Abuja to Maiduguri.
The bomber blew himself inside the Alhaji Haruna mosque next to the Monday Market just after afternoon prayers began, Borno police chief Aderemi Opadokun and witnesses said.
"The roof was blown off and fire destroyed the mats and a few Qurans," market trader Nura Khalid told the AFP news agency.
Buhari condemned the attack in a statement and vowed to take action against those responsible.
Earlier, the military repelled an overnight attack launched by men firing rocket-propelled grenades into homes in a bombardment that lasted several hours.
At least 10 people were killed in the assault that authorities said was carried out by Boko Haram fighters in a suburb of Maiduguri, capital of Borno state.
Borno has borne the brunt of many of the recent attacks by the group. The violence has forced tens of thousands of people from their homes.
Boko Haram is an armed group fighting against Western influence. The name loosely translates as "Western education is forbidden". It was behind the kidnapping of more than 200 girls from their school in Chibok in April last year. Most of the girls are still missing.
Suicide bombings and other attacks by the group have killed more than 13,000 people and displaced an estimated 1.5 million since 2009.
Buhari in his inaugural speech announced plans to reinforce Maiduguri with a new command and control centre to better coordinate the counter-insurgency effort.
The group has been flushed out of several Borno towns they controlled in an offensive launched in February by Nigeria with backing from neighbouring Cameroon, Chad and Niger.
But there are signs of the fighters regrouping, particularly in the remote parts of eastern Borno near the Cameroon border.
Source: Al Jazeera and agencies