Lusaka - Zambians went to the polls Thursday to elect a successor to deceased president Levy Mwanawasa in a tense contest between a government veteran promising stability and a charismatic populist. 

Although there are four candidates vying to replace Mwanawasa, who died in August after suffering a stroke, however, ruling Movement for Multi-Party Democracy (MMD) candidate, acting president Rupiah Banda, and opposition Patriotic Front leader Michael Sata are deemed to be the only serious contenders. 

Voting was scheduled to get underway at 6 am (0400 GMT) at 6,456 polling stations across the southern African country. Only 3.9 million Zambians out of an estimated 11.7 million are registered to vote. The Electoral Commission of Zambia said first results could be in by Friday. 

The army is on alert and police have been deployed at all polling stations amid fears of a repeat of the violence that gripped the 2006 election. Sata's initial refusal to accept defeat at the hands of Mwanawasa sparked days of rioting. 

Buoyed by large turnouts at his rallies - bigger than at Banda's - Sata, 71, has threatened to again reject the outcome of the election if he suspects rigging in favour of Banda. 

The opposition leader, nicknamed King Cobra for his attacking political style, promises more pro-poor policies and a greater stake for Zambians in the flagship mining industry. He was tipped to win in two out of three opinion polls published in the run-up to the vote. 

Banda, also 71, who has campaigned on a theme of continuity with the popular Mwanawasa's prudent economic policies, was damaged by a bitter succession race within the MMD after Mwanawasa's death. 

The election takes place against the backdrop of plummeting prices for copper - Zambia is Africa's biggest producer of the metal - as slower global growth depresses demand. 

Despite its resource wealth, Zambia is ranked among the poorest countries in the world, where about 65 per cent of people live on less than a dollar a day (dpa)