Terrified families packed their bags at both ends of the oil-producing country of 110 million to return to ethnic homelands, with fears running strong of a repeat of reprisal killings which have followed previous clashes.
The fighting has set Nigeria's main tribes against each other -- Hausas from the mostly Muslim north and ethnic Yorubas from the more heavily Christian and animist southwest around Lagos, the country's biggest city and commercial capital.
Troops in battle dress guarded the smoldering Mushin slum district in Lagos and other potential flashpoints, as they have been called to do many times since military rule ended in 1999.
Lagos Governor Bola Tinubu said he believed the clashes, an arms dump explosion on January 27 that caused 1,000 deaths and a police mutiny had all been instigated by retired military officers to bring about a return of army rule.
"We know from intelligence reports what is happening. Retired military officers are not happy with what is going on. They are not happy with democracy and transparency," Tinubu told Reuters in an interview on Tuesday.
The violence has overshadowed a visit by British Prime Minister Tony Blair, who is expected to arrive in Nigeria's capital Abuja late on Wednesday and meet President Olusegun Obasanjo on Thursday. Nigeria, Africa's most populous country, is a former British colony.
The Nigerian Red Cross said it was taking care of 3,000 people who fled the fighting in Lagos, alongside thousands more made homeless by the arms dump explosion.
"Bodies have mostly been cleared from the streets," said a senior Red Cross official. "Now we need tents and we need beds. With the damage that has been done many people will not be returning to their homes for at least two weeks."
Some were not expecting to return at all.
In Mushin, and other parts of Lagos with big Hausa communities, families packed their bags to return to the north. Some Yorubas set off from northern cities, fearing there would be reprisals there.
"Most people here have evacuated their wives and children back to the north," said Tijani Alhassan in Mushin.
"The men are staying back but their families may never come back to Lagos. If you are alone and trouble starts it is easier for you to take care of yourself."
In Kano, the biggest city in the north and scene of ethnic and religious violence that left hundreds dead last year, police said they had asked Lagos authorities not to allow the bodies of dead Hausas to be brought home.
That has triggered reprisal killings in the past.
"There is fear everywhere. Kano could turn in the next few days," said one Yoruba man in his 50s as he prepared to head for the southwest with several dozen other Yorubas.
Nigeria has been ruled y the army for all but a dozen years since independence from Britain in 1960.
Africa-wide problems and the political and economic crisis in Zimbabwe were initially expected to dominate Blair's visit, but Nigeria's latest series of woes have again marked it out as potentially the continent's most explosive source of grief.
Africa's most populous nation is riven with ethnic, religious and political divides. Thousands have been killed in periodic clashes since President Obasanjo won 1999 elections ending 15 years of brutal military rule.
The latest violence came on the heels of explosions at a Lagos army munitions depot that killed more than 1,000 people last week. Many of those who died were women and children who fell into a canal and drowned during a late-night stampede to escape the blasts.
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