Mr Biya secured 71% of the vote in the 7 October election but opposition parties said the election was marred by fraud.

The ceremony was clouded by Monday's kidnapping of 80 people, including 79 students, in a school in the restive North-West region.

The government and separatists - who are pushing for an independent state in mainly English-speaking areas - have been trading accusations as to who is behind the kidnapping. More than 300,000 people have fled the violence in the North-West and South-West regions with some crossing the border into Nigeria.

The conflict started in 2016 after residents of the mainly Anglophone regions alleged that the French-speaking majority was discriminating against them in schools and courts.