The party of Nigeria's president-elect Muhammadu Buhari has won governorship elections in a majority of Nigeria's 36 states, building its strength nationwide after a historic presidential win, official results on Monday showed.

The All Progressives Congress took control of at least 19 governor's seats following Saturday's closely-fought regional polls but could add to that tally with results from several states still pending.

President Goodluck Jonathan's People's Democratic Party had controlled the federal and most state governments since the end of military rule in 1999, but suffered major losses during Nigeria's gripping 2015 election cycle.