Nigerian President Muhammadu Buhari said on Wednesday he would focus on consolidating his achievements to take the country to the "next level" during his second term of office.

Early Wednesday, the country's electoral body, the Independent National Electoral Commission (INEC), declared Buhari the winner of the presidential election.

Buhari, in his acceptance speech, said many focal areas, as stated in his campaign manual, will be included in what he had in plan for the country.

"I can assure that you will see a country moving to the next level, as we consolidate on our fundamental areas of securing the country, reviving the economy, and fighting corruption," the 76-year-old president said.

Buhari, the candidate of the governing All Progressives Congress (APC) party, topped last Saturday's presidential poll with more than 15 million votes, or 55.6 percent of the total ballots, according to INEC Chairman Mahmood Yakubu.

The runner-up was Atiku Abubakar of the main opposition People's Democratic Party (PDP), who garnered over 11 million votes or 41.2 percent.

Yakubu announced the final results here after a three-day collation of polls from the country's 36 states, including the capital Abuja.

In Nigeria, the candidate with the most votes is declared the winner as long as they have at least 25 percent of the vote in two-thirds of Nigeria's states.

Buhari won in 19 states, mostly in the northern part of the country -- his stronghold since 2003.

INEC on Wednesday afternoon presented a certificate of return to Buhari, and vice president Yemi Osinbajo, in the Nigerian capital. The certificate presented to them formally validates their re-election into office.

Buhari said he and his team will roll up their sleeves afresh, and give their best in his second term of office.

"The hard work to deliver a better Nigeria continues, building on the foundations of peace, rule of law and opportunities for all," he said. "We have no other motive than to serve Nigeria with our hearts and might, and build a nation which we and generations to come can be proud of."

Nigeria, Africa's largest economy, is faced with many challenges, including unemployment, insecurity, corruption, and wasteful culture, to mention a few.

In his "Next Level 2019" slogan launched ahead of his re-election campaign, the Nigerian leader put the provision of more jobs, promoting infrastructure development and enhancing the business environment ahead of security and fighting corruption.

Xinhua