Zambia's opposition Patriotic Front said it would go to court on Tuesday to demand a recount of a presidential ballot in which centrist politician Rupiah Banda was elected by a narrow margin, reported Reuters.
Opposition leader Michael Sata has branded the election, triggered by the death of Levy Mwanawasa in August from a stroke, as a fraud.
"They are still preparing certain documents and they will be filing them tomorrow," Patriotic Front spokesman Given Lubinda said on Monday.
The court petition would call for a recount of Thursday's ballot and verification of the votes that were cast, he said.
Zambia has been one of the most politically stable countries in Africa, but a prolonged election dispute could unsettle investors at a time when the world's 10th largest copper producer is feeling the pinch from the global financial crisis.
Banda, sworn in as president on Sunday, had been acting head of state since Mwanawasa's death and had campaigned to maintain the business friendly policies of his predecessor.
He won 40 percent of the 1.79 million votes cast against 38 percent for Sata, according to final results released by the electoral commission. The margin of victory was 35,209 votes.
During the election campaign, Sata portrayed himself as a champion of the poor and said if elected he would act to get foreign companies to sell equity stakes to Zambians.
Foreign lenders and investors praised Mwanawasa for conservative fiscal policies credited with fuelling an economic boom in the southern African country where growth has averaged 5 percent per year since 2002.