Banda, the country's acting head of state, emerged victorious from the controversial vote while Sata's opposition Patriotic Front party said it would go to court to demand a recount, the BBC reported Sunday.
Sata has rejected the result, saying the election was stolen by Banda, but the African Union and the 15-nation Southern African Development Community disagreed with the claims of fraud.
Riot police fired tear gas at Sata's supporters Saturday night as they marched through a Lusaka slum neighborhood, setting fires and throwing stones in the streets, the BBC said.
Late Saturday, results showed Banda with 708,683 votes versus 682,171 for Sata based on counts from 148 of 150 constituencies, the South African Broadcasting Corp. said.
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