Photos from President Buhari's inauguration

Muhammadu Buhari has been sworn in as the 15th president of Nigeria.

Mr. Buhari is the first opposition figure to win a presidential election in Nigeria's 55 years of independence.

He took over from Goodluck Jonathan, who has urged his successor to unite the country in the face of the threat from Boko Haram militants.

Mr. Buhari, a former military ruler, says he is a convert to democracy.

"I belong to everybody and I belong to nobody", he told cheering crowds at the inauguration in the capital, Abuja.

He vowed to tackle "head on" the issues of corruption and the insurgency from militant Islamist group Boko Haram.