Polls opened in Zambia early on Thursday to elect a new president, with police and soldiers on alert for fear of violence by opposition supporters who accuse the government of planning to rig the ballot.

Doors to the polling stations opened at 6am (0400 GMT) for the election called to choose a successor to president Levy Mwanawasa, who died in August.

Police and the military fear the election could spark unrest after opposition leader Michael Sata of the Patriotic Front accused election officials of planning to rig the ballot in favour of acting President Rupiah Banda.

Sata (71) had urged his supporters to sleep outside polling stations to prevent any attempts at fraud, and has already warned that he will not accept the results if he loses and suspects vote-rigging.

The fiery populist, whose rhetoric earned him the nickname 'King Cobra', lost the last election in 2006 to Mwanawasa. His supporters rioted for days afterward, although he insists he never condoned the violence.

AFP