Nigeria's president Muhammdu Buhari and his top challenger Atiku Abubakar in Saturday's election have signed a pledge of peace ahead of a vote marked by heated accusations that have alarmed some observers.
President Muhammadu Buhari, who seeks a second term, and former Vice President Atiku Abubakar on Wednesday vowed to participate in a free and fair election in Africa's most populous country without "religious incitement" or ethnic profiling.