In a New Year message, Mr Buhari said he would not attempt to exceed the constitutional mandate.

The president said he was determined to help strengthen the electoral process both in Nigeria and across the region, and cited his primary concerns as the security of the nation and the safety of Nigerians.

A BBC correspondent says speculation that Mr Buhari planned to remain in power has been rife in recent days.

President Muhammadu Buhari was elected for a second four-year term last year