Nigeria election: Politicians urged to stop violence
Politicians in Nigeria should put a stop to campaign violence ahead of national polls on Saturday, Amnesty International has said.
The rights group says at least 20 people have died in political attacks and clashes over the last two weeks.
Nigerians will be voting over three weekends - first in legislative, then presidential and lastly in state polls.
It is the third time general elections are being held in Nigeria since military rule ended in 1999.
The previous ones - in 2003 and 2007 - were marred by allegations of widespread rigging, voter intimidation and ballot vote snatching.
Security forces were also accused of siding with the ruling People's Democratic Party (PDP), which has dominated politics since the return to civilian rule.
Nigeria is Africa's leading oil producer and most populous nation, but more than half of its 160 million citizens live in poverty.
It has also been bedevilled by occasional outbreaks of deadly violence between the country's numerous ethnic groups over the last 12 years.
Muhammad Jameel Yushau, of the BBC's Hausa Service, says the PDP currently has firm control of both the upper and lower chambers of the National Assembly, but Saturday's elections are expected to be a stern test for the party.
The 74m registered voters will then vote in presidential polls on 9 April - and for local assemblies and the powerful governors of Nigeria's 36 states the weekend after.
Amnesty International says some of the worst political violence has been in the southern state of Akwa Ibom.
Other clashes have taken place in south-western Ekiti state, Jigawa state and Bauchi state in the north and Bayelsa in the oil-rich Niger Delta, home state to President Goodluck Jonathan.
"We receive consistent reports that politicians, both candidates and those in office, instigate political violence, despite their statements to the contrary," Tawanda Hondora, Amnesty International's deputy director for Africa, said in a statement.
This week, tens of thousands of extra security forces have been deployed across the country.
The BBC's Peter Okwoche in the capital, Abuja, says he has seen rows of new police vehicles lined up outside the police headquarters on the eve of the polls.
Meanwhile, the independent electoral commission has been deploying more than 400,000 staff.
Election material is being taken to polling stations by plane, boat and road.
Poor infrastructure and difficult terrain have caused serious delays in previous polls, with voting material sometimes arriving two to three days after the election.
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.