Anti-government protests in the Bolivian region of Potosi have entered a third week, hitting mining production and disrupting normal life.
A Japanese-owned silver, zinc and lead mine has had to suspend many of its operations and other mines have also seen output disrupted.
With road and air links blocked, food supplies are running low and some foreign tourists have been stranded.
Protesters are demanding government investment in their region.
Bolivia's mining minister Jose Pimentel said several hundred protesters had occupied a hydroelectric station that supplies the San Cristobal mine.
The mine, owned by Japan's Sumitomo Corp, had partially stopped production in the southern Potosi region, a company spokesman told Reuters.
It is one of the world's largest mines, ranking third in silver output and sixth in zinc, according to Sumitomo.
Other mines in the region have also been affected, including several run by foreign companies, among them Coeur d'Alene Mines Corporation of the US and Switzerland-based Glencore.
Potosi, Bolivia's key mining region, has been hit by a general strike and protests for the past fortnight.
Protesters have also been staging hunger strikes.
Demonstrators have several demands, including the settlement of a boundary dispute with the neighbouring province of Oruro.
They also want more investment, including the expansion of the airport, new roads and the construction of a cement factory.
The government has insisted it will not use force to break the blockade.
The solution would come via dialogue, presidential spokesman Ivan Canelas said.
He also defended the central government's record of investment in the region.
Food stocks have been running low and there have been long queues at banks as customers try to withdraw cash.
The blockades have made it difficult for tourists to get out of the historic city of Potosi.
Some 30 foreign visitors managed to leave Potosi earlier in the week, but several are still there.
The UK Foreign Office said it was offering consular assistance to a number of British nationals, and is advising against all travel to the Potosi/Uyuni region.