Muhammadu Buhari has been re-elected as president of Nigeria for a second four-year term.

The 76-year-old defeated his main rival, Atiku Abubakar, with a margin of just under four million votes.

Abubakar, the former Vice President, and his People’s Democratic Party have rejected the result.

Final results released by the Nigerian electoral commission (Inec) show Buhari was re-elected with a margin of just under four million votes.

Turnout was just below 35% of registered voters.

Delays and violence marred the run-up to the poll but no independent observer has cited electoral fraud.

Buhari has promised to build on his accomplishments in office so far, while Abubakar, a business tycoon, has accused the president of wasting his term.

Saturday’s general elections were marred by violence and voter intimidation. As many as 39 people have been killed in election violence, civil society groups said on Sunday.

The African Union observers have expressed concern about delays and logistical problems with Saturday’s elections but said it was free and fair. 

“The 2019 elections took place in a generally peaceful environment,” said AU observer mission head Hailemariam Desalegn, the former prime minister of Ethiopia.