La Paz: Bolivia on Saturday formally accused three miners of the murder of deputy interior minister Rodolfo Illanes this week, including the president of the federation that had organised protests and a roadblock.
The killing of Illanes, who was found beaten to death after being kidnapped on Thursday by miners demanding changes in the law, has shocked Bolivia and presented leftist President Evo Morales with one of his greatest challenges since taking power in 2006.
The public prosecutor accused three miners of the murder, including Carlos Mamani, the president of the National Federation of Mining Cooperatives of Bolivia.
Last week, the group blocked a highway linking capital La Paz with the city of Oruro. At least two miners were killed and 17 police injured in clashes, and the government said Illanes had approached the protesters to attempt dialogue.
The miners, who work in co-operatives rather than for private companies, have been hit by the global commodities downturn and were demanding that the government relax environmental restrictions and increase subsidies.
Mamani, who was arrested on Friday, was formally accused of murder, aggravated robbery, criminal organisation, possession of firearms and attacking members of state security.
A hearing will be held this weekend.
The roadblock has been abandoned and the protests have ended, authorities said.
Morales described the protests as a "political conspiracy" against his government, carried out with backing from the right-wing opposition.
"Now we are getting information and finding documents that say this is to take down the government," he told a news conference.
Opposition leaders denied any involvement.
"We ask the president in this sad hour not to weave false conspiracy theories," said ex-president Jorge Quiroga.
The government has ruled out talks with the miners and asked for the maximum 30-year jail sentence for those found guilty.
Ex-coca grower Morales is one of the last leaders left standing from South America's once-dominant populist leftist bloc.
His policies to redistribute the wealth of a natural gas windfall and empower once marginalised groups won him many admirers in the early years. More recently his government has been dogged by accusations of cronyism, while it has struggled to keep up with supporters' demands at a time when incomes are tight.
Illanes, 56, was a long-time Morales ally appointed as deputy minister in March. His funeral will take place in La Paz.