Nigerians flee Boko Haram sectarian attacks
Hundreds of people have been fleeing areas of north-eastern Nigeria, after a 24-hour wave of violence apparently targeting Christian communities.
At least 29 people have died in four attacks in Adamawa state, prompting the state governor to impose a curfew.
The Islamist Boko Haram group has said it carried out several attacks.
One Boko Haram faction has warned all southerners - who are mostly Christian and animist - to leave the mainly Muslim north of Nigeria.
Last week President Goodluck Jonathan declared a state of emergency in Yobe and Borno states, as well as Plateau state in central Nigeria and Niger state in the west, following a surge in ethnic and sectarian violence.
Adamawa, which borders Borno state where Boko Haram emerged, was not included.
More than 500 people have been killed by the group over the past year.
President Goodluck Jonathan, who is a Christian, said security forces would enforce the law "without fear or favour".
"I urge all Nigerians to eschew bitterness and acrimony to live together in harmony and peace," he said on Saturday in a televised address.
But Christian groups have accused the government of not doing enough to protect them.
Pastor Ayo Oritsejafor, president of the Christian Association of Nigeria, said his members would protect themselves against the attacks.
"We have the legitimate right to defend ourselves. We're also saying today that we will do whatever it takes" he said.
The pattern of the killings suggested "systematic ethnic and religious cleansing", he added.
The pastor declined to be specific about how Christians would defend themselves, raising fears of retaliation and an escalation of the violence.
At least 17 people were killed in Mubi, in Adamawa, as gunmen opened fire in a town hall where members of the Christian Igbo group were meeting.
They had been meeting to organise how to transport the body of an Igbo man who was shot dead by gunmen on motorbikes on Thursday evening.
"It was while they were holding the meeting that gunmen came and opened fire on them," a resident said.
More attacks on a church and hairdressing salon in Adamawa's capital, Yola, left more than 10 dead.
The attacks prompted state governor Murtala Nyako to impose a 24-hour curfew.
Security was tightened and troops were seen patrolling the streets.
A resident in Yola says all shops and businesses are closed and only essential services are being allowed through the deserted town.
Fear of soldiers
Meanwhile people fled the streets of the town of Potiskum, in Yobe state, after an attack on banks and the police headquarters followed by a shoot-out between gunmen and security forces.
"We are afraid the soldiers will raid and burn our homes like they do in Maiduguri each time Boko Haram attack," local resident Amiru Umar told AFP.
The Islamist Boko Haram group said it had carried out the attacks in Mubi and Yola, and another in Gombe on Thursday night in which at least six people died.
The group has staged numerous attacks in northern and central areas in recent months - on Christmas Day it attacked a church near the capital, Abuja, killing dozens of people.
Boko Haram, whose name means 'Western education is forbidden', is fighting to overthrow the government and create an Islamic state.
Meanwhile, the government is also facing the bleak prospect of a general strike in two days' time amid popular fury over its removal of a fuel subsidy which has seen fuel prices double for ordinary Nigerians.
The BBC's Mark Lobel in Lagos says the strike will overstretch the military, which already appears to have lost control of the situation in the north-east.
In his TV address on Saturday, Mr Jonathan announced new austerity measures which he said were designed to help mitigate the pain felt by higher fuel prices.
The measures included the cutting of government salaries by 25% and a ban on all but essential official international travel, he said.
To win at the first round, a candidate not only needs the majority of votes cast, but at least 25% of the vote in two-thirds of Nigeria's 36 states. Goodluck Jonathan, of the PDP, reached that threshold in 31 states; runner-up Muhammadu Buhari of the CPC only did so in 16 states.
Nigeria's 160 million people are divided between numerous ethno-linguistic groups and also along religious lines. Broadly, the Hausa-Fulani people based in the north are mostly Muslims. The Yorubas of the south-west are divided between Muslims and Christians, while the Igbos of the south-east and neighbouring groups are mostly Christian or animist. The Middle Belt is home to hundreds of groups with different beliefs, and around Jos there are frequent clashes between Hausa-speaking Muslims and Christian members of the Berom community.
Despite its vast resources, Nigeria ranks among the most unequal countries in the world, according to the UN. The poverty in the north is in stark contrast to the more developed southern states. While in the oil-rich south-east, the residents of Delta and Akwa Ibom complain that all the wealth they generate flows up the pipeline to Abuja and Lagos.
Southern residents tend to have better access to healthcare, as reflected by the greater uptake of vaccines for polio, tuberculosis, tetanus and diphtheria. Some northern groups have in the past boycotted immunisation programmes, saying they are a Western plot to make Muslim women infertile. This led to a recurrence of polio, but the vaccinations have now resumed.
Female literacy is seen as the key to raising living standards for the next generation. For example, a newborn child is far likelier to survive if its mother is well-educated. In Nigeria we see a stark contrast between the mainly Muslim north and the Christian and animist south. In some northern states less than 5% of women can read and write, whereas in some Igbo areas more than 90% are literate.
Nigeria is Africa's biggest oil producer and among the biggest in the world but most of its people subsist on less than $2 a day. The oil is produced in the south-east and some militant groups there want to keep a greater share of the wealth which comes from under their feet. Attacks by militants on oil installations led to a sharp fall in Nigeria's output during the last decade. But in 2010, a government amnesty led thousands of fighters to lay down their weapons.