Nigeria election: Red Cross says many fleeing violence
Tens of thousands of people have fled their homes because of post-election violence in Nigeria, the Red Cross says.
Riots broke out in the north after Goodluck Jonathan, a southerner, emerged as the winner of the presidential poll.
A civil rights group says the unrest has left more than 200 dead, while hundreds of arrests have been made.
The poll runner-up, General Muhammadu Buhari, has appealed for calm.
Nigeria is divided by rivalry between the predominantly Muslim north and the mainly Christian south - so much so that the presidency has often rotated between people who come from the two halves of the country, in an attempt to keep the peace.
Umar Marigar of the Red Cross told the BBC on Wednesday that the number of displaced had trebled in the last day - from 16,000 to 48,000, mainly in the north.
But he said that, in the southern state of Anambra, 8,400 people had sought refuge at the Onitsha military barracks because they feared reprisal attacks against northerners.
Both the winner of Nigeria's election, Goodluck Jonathan, and his main rival, Muhammadu Buhari, have called for calm following the post-poll riots in the north. But the tensions cannot be plastered over.
Most of those behind the rioting have been unemployed young men - uneducated and deprived. Often they are only remembered by politicians at elections, when they are sometimes paid to do their bidding. They could send any conflict out of control, because it provides them with an opportunity to loot and attack the people they perceive as their enemies.
Irrespective of political party and region, 12 years of civilian rule have brought little change to the lives of Nigerians. But the north is far behind the south in terms of development, education and the availability of economic opportunities. Good governance, not political platitudes from the elite, is what many say is needed for the future.
He added: ''The violent protests turn from political into ethno-religious crisis. As such, people might like to engage in retaliatory attacks. This is what we are always afraid of."
Shehu Sani, head of the Civil Rights Congress, told the AFP news agency: "In the whole region, from reports reaching Civil Rights Congress, the death toll is over 200."
He added that more than 1,000 people had been arrested in the city of Kaduna alone.
The BBC's Abdullahi Kaura Abubakar says Kaduna city is now calm, with markets open and people shopping for food.
The security forces are patrolling the streets and police helicopters can be heard flying overhead intermittently.
The streets of the city were left littered with charred corpses after rioters burned churches, police stations and homes during two days of disturbances.'Irregularities'
Gen Buhari told the Voice of America's Hausa-language radio service that his Congress for Progressive Change party had noticed irregularities in the south and south-east of the country.
"I urge people to calm down and be law-abiding as we are pursuing these irregularities with [the electoral commission] with a view to ensure justice for them," he said.
Mr Jonathan was declared winner of Saturday's presidential poll, with the electoral commission saying he received about 57% of the vote with 22.5 million votes to General Buhari's 12.2 million votes.
International observers have said the election was reasonably free and fair.
Mr Jonathan, a Christian from the oil-producing Niger Delta, was appointed to the presidency last year upon the death of incumbent Umaru Yar'Adua, a northern Muslim whom he had served as vice-president.
He staked his reputation on the election, repeatedly promising it would be free and fair.
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.