Nigeria's president-elect Bola Tinubu has appealed for unity in an address to jubilant supporters after being announced the winner of Saturday's election.

The former governor of Lagos said he wanted to work to make Nigeria great.

Mr Tinubu, from the governing All Progressives Congress, won almost nine million votes, two million more than his nearest rival.

But opposition parties have called for the poll to be cancelled, alleging result manipulation.

There has been widespread concern about the slow counting of the votes.

The electoral commission rejected the accusations.

Mr Tinubu will take over from Muhammadu Buhari who is stepping down after two terms at the age of 80.