The leftist anti-US activist, Evo Morales, has claimed a decisive victory in Bolivia's presidential election, and is set to become the country's first indigenous head of state.

Exit polls have placed the 46-year-old well ahead of his nearest rival the right-wing former president, Jorge Quiroga, who has conceded defeat. Official results from yesterday's vote are not expected for several days.

Mr Morales has promised supporters he will be a thorn in the side of the United States.