Gunmen shot eight people dead in northern Nigeria Tuesday and a mob torched an Islamic school in the south, as a nationwide fuel strike and growing religious tension rattled Africa's oil-rich giant.
The two-day old general strike has not yet affected the output of Africa's top oil producer but it has paralysed the country and sent the government, already battling a brutal campaign by an Islamist group, into crisis mode.
Suspected members of the extremist Boko Haram sect gunned eight people down in a pub as one of Nigeria's most respected voices, Nobel prize in literature laureate Wole Soyinka, warned the country was heading towards civil war.
A doctor in Potiskum, a town in the northern state of Yobe, said eight bodies were brought to the morgue after militants stormed a pub and opened fire before speeding away on a motorcycle.
"The bodies included five policemen, a bartender, a customer and a 10-year-old girl," the doctor said.
The police confirmed the shooting but did not provide a casualty toll.
Earlier, attackers burnt part of the central mosque complex in the southern city of Benin, where clashes earlier killed five, bringing to 11 the number of people killed in incidents related to the strike over two days.
"We have recorded so far five deaths -- on both sides, those that have been attacked and the attackers," said Dan Enowoghomwenwa, secretary general of the Nigerian Red Cross in Edo state, told AFP.
He said 10,000 people were also displaced by the violence.
Witnesses said an Islamic school adjacent to the mosque was burnt on Tuesday as was a bus parked next to it.
The attacks in Benin city started on Monday amid street protests against soaring fuel prices, when a crowd separated from the main demonstration to attack another mosque and terrorised residents of mainly Hausa neighbourhoods.
Hausas are the largest ethnic group in Nigeria's north and are overwhelmingly Muslim.
The Red Cross official could not specify who was behind the attacks, only saying there were "indigenes" targeting northerners.
Africa's most populous nation is roughly divided between a predominantly Christian south and mainly Muslim north.
Recent violence targetting Christians in the north and blamed on Islamist group Boko Haram has sparked fears of a wider religious conflict as well as warnings from Christian leaders that they will defend themselves.
Fears run high that the strike will fan sectarian tensions and Soyinka, who became Africa's first laureate of the Nobel for literature in 1986, warned in a BBC interview that Nigeria was heading towards a conflict akin to the 1960s war.
"It's not an unrealistic comparison - it's certainly based on many similarities... We see the nation heading towards a civil war," the writer said.
Elsewhere in the country, gangs set up burning roadblocks, police fired tear gas and businesses shut in the many parts as the national strike over fuel prices paralysed Nigeria.