Nigeria is counting votes after a polling day fraught with delays and frustrations.

And it's too close to call who will be the next president of Africa's biggest economic power.

The outcome hinges on which of the two main rivals voters trust to sort out an economy still struggling to recover from a 2016 recession.

Incumbent President Muhammadu Buhari, a former military ruler who was later elected in, sounded pretty confident about his chances of a second term: (SOUNDBITE) (English) NIGERIAN PRESIDENT, MUHAMMADU BUHARI, SAYING: "I will congratulate myself, I'm going to be the winner.

Thank you very much." As did his rival Atiku Abubakar -- a former vice president who has pledged to boost the private sector.

Once people were able to get in to polling stations that often opened hours late, voting went off largely peacefully.

It had already been delayed by a week -- called off last Saturday hours before polls were meant to open.

Two attacks were reported in the northeast, where Islamist insurgents Boko Haram had warned people not to vote.

One occurred in the town of Geidam -- but people fled and the army said there were no casualties.

And a group called Islamic State West Africa Province claimed it had carried out another attack in Maiduguri, in a neighbouring state, after blasts were heard.

Nigeria's army said that didn't happen; putting the blasts down to exercises by the military.

Officials said the voting was extended in areas where polling centers opened late or ballot machines had failed.

And that polling was transparent in the vast nation of 73 million eligible voters.