LA PAZ, Bolivia (AP) — Striking informal miners in Bolivia kidnapped and beat to death the country’s deputy government minister after he traveled to the area to mediate in the bitter conflict over mining laws, officials said late Thursday.

Government Minister Carlos Romero called it a “cowardly and brutal killing” and asked that the miners turn over the body of deputy minister Rodolfo Illanes.

Earlier, Romero said that Illanes had been kidnapped and possibly tortured, but local media reports that he had been killed by the miners had not been confirmed.

But late Thursday Romero and Defense Minister Reymi said that the vice minister of government had been beaten to death by the miners, who are demanding more rights, including the right to associate with private companies.

Illanes had gone to Panduro, a town 80 miles (130 kilometers) south of the La Paz, where the strikers have blockaded a highway since Monday, to open a dialogue. Thousands of passengers and vehicles are stranded on roads blocked by the strikers.

The strike has turned violent recently with two protesters being killed and riot police failing to clear a highway in a western part of the mining-dependent Andean nation.

Bolivia’s informal or artisan miners number about 100,000 and work in self-managed cooperatives. They want to be able to associate with private companies, which is currently prohibited. The government argues that if they associate with multinational companies they will cease to be cooperatives.

The National Federation of Mining Cooperatives of Bolivia, once strong allies of President Evo Morales, went on an indefinite protest after negotiations over the mining legislation failed.