<span style="color: #222222;">Nigerian President Muhammadu Buhari has been re-elected for a second four-year term, after the election commission on Wednesday declared the results of the poll plagued by claims of rigging. </span><br />'' <br />'' <span style="color: #222222;">76-year-old Buhari defeated his main rival, former Vice-President and country's opposition leader Atiku Abubakar, with a margin of nearly four million votes. </span><br />'' <br />'' <span style="color: #222222;">Hours after Buhari was declared winner, Abubakar rejected the results and vowed a legal challenge. His People's Democratic Party (PDP) has alleged electoral malpractice in the polls. </span><br />'' <br />'' <span style="color: #222222;">Voting for the presidential elections on February 23 was marked by hours-long delays and deadly violence. </span><br />''