Nigeria: Buhari promises to tackle Boko Haram

The winner of Nigeria's presidential election, General Muhammadu Buhari, has singled out the threat of the militant Islamist group Boko Haram as the biggest problem facing the country.

Gen Buhari, who was a former military ruler, now describes himself as a reformed democrat.

He told the BBC's Peter Okwoche he needed the co-operation of other countries to tackle Boko Haram more quickly.