Zambia's main opposition party is asking officials to stop releasing the results of the country's presidential election, while renewing charges that the election was rigged.

Opposition leader Michael Sata's lead over acting President Rupiah Banda has narrowed to about 13,000 votes, as results from rural areas, where Mr. Banda has strong support, come in. 

Sata stormed the country's election center in Lukasa Saturday and charged the voter rolls must have been inflated, saying that is the only way he could be leading Mr. Banda by so little. 

Despite the complaints, an observer team from the Southern African Development Community (SADC) declared Saturday the elections were free and transparent.

So far, 137 of Zambia's 150 constituencies have reported results from Thursday's election to fill the seat of President Levy Mwanawasa, who died in August following a stroke. 

Turnout for Thursday's vote appears to have been less than 50 percent, which election monitor Leshele Thoahlane of the Electoral Institute of Southern Africa characterized as low.

Sata campaigned as a champion of the poor, while Mr. Banda portrayed himself as someone who would continue the business-friendly policies of Mr. Mwanawasa.

Sata's supporters took to the streets after he lost Zambia's 2006 election to Mr. Mwanawasa.  Sata blamed his loss in that poll on massive ballot-rigging.  The results were later upheld. 

Some information for this report was provided by AFP and Reuters.