Citizens are going to the polls today after a last-minute postponement earlier this week.
The main challenger to reigning president Muhammadu Buhari is former Vice-President Atiku Abubakar.
It is not known exactly when the final results will be announced.
Experts say a winner could be declared as late as Tuesday.
Nigeria is Africa's most populated country.
European leaders rally behind Greenland in face of renewed US threat
Leaders from major European powers rallied behind Greenland on Tuesday, saying the Arctic island belongs to its people, following a renewed threat by US President Donald Trump to take over the Danish territory.
6.7-magnitude earthquake strikes near Baculin, Philippines
A 6.7 magnitude earthquake struck off the Philippines' southern islands on Wednesday, the US Geological Survey (USGS) said, and there were no immediate reports of damage or injuries.
Israel, Syria to share intelligence following US-mediated talks
Israel and Syria agreed during US-mediated talks in Paris to set up a communication mechanism to coordinate on security, intelligence and commercial issues, the three countries said in a joint statement released on Tuesday by the State Department.
Maduro opponent Machado vows to return to Venezuela, wants election
Venezuela's main opposition leader Maria Corina Machado has vowed to return home quickly, praising US President Donald Trump for toppling her enemy Nicolas Maduro and declaring her movement ready to win a free election.
Ukraine security guarantees to include binding commitments: draft Paris summit
Security guarantees for Ukraine will include 'binding commitments' to support the country 'in the case of a future armed attack by Russia in order to restore peace', a draft statement from the "Coalition of Willing" of Kyiv's allies, showed on Tuesday.
