Elections in parts of Nigeria have been extended until Sunday
after delays and a number of attacks.
The delays were "not widespread" but were still "a matter of
concern", an election official told the BBC.
Technical problems with new biometric cards slowed down
voter registration, even affecting President Goodluck Jonathan.
More than a dozen people have reportedly been killed in
various attacks by unknown gunmen
Goodluck Jonathan is facing a strong challenge from Muhammadu
Buhari.
The election is said to be the most closely fought since
independence.
It was postponed from mid-February to allow the army to
recapture territory from the Islamist militants of Boko Haram.
The two main candidates had pledged to prevent violence
during and in the aftermath of the elections.
But several hours after voting started, reports came in of
violent incidents at polling stations in which at least 13 were
reported to have been killed.