US President Barack Obama on Monday met with his Nigerian counterpart Muhammadu Buhari, who started a four-day visit to Washington.

The meeting dealt with efforts to bolster the fight against militant group Boko Haram and various issues of common concern.

At the outset of the meeting, Obama praised the March elections won by Buhari as "an affirmation of Nigeria's commitment to democracy."

Buhari replied by saying Nigeria will "ever be grateful" for the US help in ensuring the elections were free fair and credible.