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The tanks move in to quell the protests that have brought Bolivia - South America's poorest nation - to a virtual halt.

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Troops attempt to clear the roadblocks set up by protesters in a bid to choke food and fuel supplies to La Paz.

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The government's plan to export natural gas to the United States through Chile sparked the month-long protest.

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El Alto was the scene of violent weekend clashes - which left at least seven dead, including a five-year-old boy.

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It brings the death toll over the last month to at least 16, with dozens more injured.

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Despite the crackdown, violence could escalate in coming days as coca farmers are expected to join the protests.