The 85-year-old politician emerged winner of the poll on Monday after he won 71.3 per cent of votes, according to official results.
There were calls by the opposition last week for a re-run of the election, but the Constitutional Council rejected the move.
Major cities were under heavy security on Sunday to ward off any attempt to protest the eventual declaration of the results.
Biya has been in power for more than 35 years.
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