Nigeria has ordered the closure of all its land borders during Saturday's firmly challenged races.
The order is intended to ensure that the "elections are free, fair and absent any trace of peculiarities", the Nigeria Migration Service said.
Line authorities have been told to ensure severe authorization of the order.
The presidential and parliamentary decisions are accounted for to be the most firmly challenged since military rule finished in 1999.
The migration service said it had held onto 6,000 electors cards and other Nigerian ID reports from unlawful outsiders in the approach the elections.
President Muhammadu Buhari had before on Thursday encouraged security organizations to be "firm and gutsy" in the political race period, and cautioned against riots after the declaration of political race results.