AREQUIPA, Peru (Reuters) – Thousands of Peruvian wildcat miners were locked in a tense standoff with police yesterday after six people were killed during a protest against stricter environmental controls imposed by the government.

The violence broke out near the town of Chala, 372 miles (600 km) south of the capital Lima, on Sunday when police tried to clear a roadblock set by the miners on the Panamerican Highway leading to Chile.

Two of the dead were bystanders, including a taxi driver struck by a stray bullet and a woman who suffered a heart attack. Police said 20 protesters and nine officers were injured in the country’s latest conflict over natural resources.

Protesters wielding clubs and rocks continued to block a stretch of the road yesterday and traffic was snarled in both directions. Interior Minister Octavio Salazar vowed to try again in the coming hours to break the blockade, where some 3,800 miners are pitted against 1,200 police officers.

President Alan Garcia, whose term has been marred by periodic clashes over his natural resources policies, said wildcat miners must pay taxes and stop polluting.

“How can we permit a savage type of mining that doesn’t pay taxes, doesn’t pay proper wages and doesn’t use modern equipment … and which continues to contaminate the Amazon?” Garcia said.

Peru is a leading exporter of zinc, copper and gold and a major importer of mercury, most of which ends up in the hands of wildcat miners who use it to isolate gold from clumps of mud and rock. Wildcat miners produce 10 to 20 percent of all gold in Peru, the world’s No. 6 producer of the precious metal.

Members of Garcia’s administration attempted to pin blame for the unrest on the left-wing Nationalist Party of Ollanta Humala, saying his party helped organize the protests.

Humala dismissed the charges as smears aimed at derailing his bid for the presidency in 2011. He said Garcia’s government has failed to avert social conflicts.

“The government wants to point fingers, yet the people to blame are in the government,” Humala said.

Financial markets tanked in 2006 when Humala nearly won the presidency. He is now a distant third in opinion polls for the next election, and Garcia, who cannot run for a second term, has said he will do everything he can to make sure a centrist candidate wins in 2011.

Miners say Garcia’s new measures, which aim to limit dredging in rivers and prevent wildcat mining in nature reserves, would leave them without jobs and that they need the work to support their families.

Environmental groups say wildcat gold miners dump toxic mercury into forests and streams.

Miners blamed police for the violence and there were conflicting reports that some protesters had guns.

“Pollution must be mitigated … but not through repression,” Teodulo Medina, head of Peru’s national association of wildcat miners, said on RPP radio.

His group represents some 300,000 miners who work in rough conditions in hundreds of informal mines in the country’s desert coast, the Andean highlands and the Amazon basin.

Residents in poor isolated towns say Garcia has pushed investment by big foreign mining and oil companies but done little to fight poverty, which affects more than a third of all Peruvians.

Two dozen people died last year in Peru’s Amazon basin as indigenous groups rejected laws designed to lure billions of dollars in investment in mining and oil concessions to the rain forest.