Nigeria election: Muhammadu Buhari re-elected as president
Nigerian President Muhammadu Buhari has been re-elected for a second four-year term, the election commission says.
The 76-year-old defeated his main rival, former Vice-President Atiku Abubakar, with a margin of nearly four million votes.
Mr Abubakar's People's Democratic Party (PDP) has rejected the result. Turnout was a record low at just 35.6%.
Delays and violence marred the run-up to Saturday's poll but no independent observer has cited electoral fraud.
"The new administration will intensify its efforts in security, restructuring the economy and fighting corruption," Mr Buhari said after his victory was officially announced.
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Overall, the APC got 15.2 million votes while the PDP received 11.3 million.
Mr Buhari swept the north, while Mr Abubakar, 72, did better in the south and east.
Although turnout was low across the country, it was higher in the northern states - one factor behind Mr Buhari's victory.
Who is Buhari?
A former soldier, Mr Buhari led a military regime for 20 months in the 1980s and was first elected president in 2015, becoming the first opposition candidate to defeat an incumbent and win the presidency.