Paramilitary police with orders to shoot on sight quelled rioting in most of Lagos yesterday, after clashes between Nigeria's biggest ethnic groups killed at least 45 people.
The latest incident in a trail of bloodshed since President Olusegun Obasanjo took office in May to end 15 years of military rule has renewed fears about the long-term future of Africa's most populous country and OPEC's sixth-biggest oil exporter.
Police said they had contained fighting in several districts of the commercial capital including Ketu, where fighting erupted on Thursday between members of Nigeria's biggest tribes, the Hausa and Yoruba.
More than 16 bodies, most charred after being set ablaze with petrol and many hacked with machetes, lay on the streets of Ketu following the deaths of at least 27 people on Thursday. Residents said 15 children and their teachers were butchered at a nursery school.
In the northern city of Kano, police, braced for a possible backlash after Muslim prayers, yesterday prevented the launch of a Hausa militant group.
In the oil-producing Niger Delta local authorities said troops had cleared ethnic Ijaw youths blamed for killing policemen, but clashes erupted for the control of Onne port between rival Eleme and Okrika minorities.
Ethnic unrest increased since the end of army rule due to a perception that power has shifted to Mr Obasanjo's Yoruba southwest from the north, which dominated since independence from Britain in 1960.
The relaxation of the grip of the dictators has also given a freer hand to militant groups, which find willing recruits among young men with few hopes amid economic stagnation.
Mr Obasanjo, a military ruler in the 1970s, has ordered police to shoot rioters on sight.
"Obasanjo is now playing around like a dictator and it cannot work. We have to sit down and discuss this amongst ourselves," said Mr Beko RansomeKuti, a Yoruba democracy campaigner under army rule who wants more autonomy for Nigeria's regions.
One million died during civil war in the 1960s, when the Ibo south-east failed to secede.
Many northerners complain that Mr Obasanjo has favoured his own Yoruba kinsmen in making appointments.
In the south-west, support has mushroomed for the separatist Yoruba Oodua People's Congress, severely repressed under military rule. Mr Obasanjo has ordered the arrest of any its members found on the street.
The Niger Delta is in the grip of violence rooted in the demand by impoverished Ijaw villagers for a greater share of the region's oil wealth, which accounts for 95 per cent of Nigeria's export earnings.
The unrest has repeatedly disrupted Nigeria's oil export lifeline, which offers its main hope for reconstruction after years of official corruption and economic decline.