Nigeria's biggest opposition party goes to court challenging President Goodluck Jonathan's election victory, alleging fraud.
Counting begins after relatively peaceful elections for Nigeria's powerful state governors - no-one was hurt when more bombs exploded in the north-eastern city of Maiduguri.
Bomb blasts kill at least three people in the north-east Nigerian city of Maiduguri, ahead of Tuesday's elections for governors across the country.
Nigerian President Goodluck Jonathan says the violence following his election is a "sad reminder" of events that plunged Nigeria into civil war in 1967.
Tens of thousands of people have fled their homes because of post-election violence in Nigeria, the Red Cross says.
A guide to the candidates, issues and background to three rounds of elections in Africa's most populous nation.
BBC reporters at polling stations countrywide
Maps reveal economic and social divisions
Politicians are all of a twitter for young voters
Jos priest has had his home burnt three times
Has religion been hijacked by Nigeria's politicians?
Anger in the north at results show Goodluck Jonathan set to win
Nigerian author urges voters not to repeat neighbour's mistakes
Can leaders resist temptation to rig poll?
Maiduguri: Islamist shootings and police brutality
How Nigerian musicians are mobilising the youth vote
The continuing influence of chiefs and emirs
Taking Martin Luther King to Nigeria's militants
Lucky by name...