The army in Bolivia is sending in troops to guard gas pipelines to guarantee exports to neighbouring Brazil and Argentina.
The move comes amid growing anti-government protests in the east, where most gas fields are situated.
Demonstrators have been blocking roads and taking over government buildings to demand that the referendum on a new constitution be suspended.
(President Evo Morales) wants to give more power to the country's indigenous and poor communities.
Bolivia has the second largest natural gas reserves in South America but they are situated in the east of the country, where Mr Morales faces his main opposition and there are growing calls for greater autonomy.
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