"The government is not interested in solving our problems caused by mining companies that contaminate land, rivers and undermine our health," he told Reuters.

An official at the Energy and Mines Ministry said the government would look into the marchers' demands.

Mining is big business for Peru, the world's No. 5 producer of copper and No. 8 of gold, and the industry earns half of this poor Andean nation's annual export income.

But a culture clash between mining companies seeking to exploit the rich mineral wealth and farmers who say their livelihood is at risk is fast becoming a headache for unpopular President Alejandro Toledo as he seeks to lure foreign investment and fulfill promises of jobs and prosperity.

In the fruit-growing northern valley of Tambogrande, for example, residents in June overwhelmingly rejected a planned $315 million gold and copper mine that the proposed investor, Manhattan Minerals Corp., says will create jobs.

Palacin said his group's members wanted technological development to help make more of their traditional farming and livestock jobs and the repeal of the so-called "law of mining servitude," whereby mining companies negotiate payment for agricultural land and the government relocates farmers.

"Southern Peru Copper Corp. contaminates our water, our pasture land, and our animals die. There are 150 families who are being thrown off their land without being given alternatives," said Lucas Serrano, from the village of Quishque in Peru's southern Andes.

"We have only exploration, not exploitation, projects in (the Quishque) area. We are not moving anyone or causing pollution," said Guillermo Vidalon, spokesman for Southern Peru, a unit of Grupo Mexico.

"Our animals are dying. There are no fish or frogs in the rivers any more. There's no life. Our children are sick because all of the mining waste is filtering into the water we drink," said Melchora Surco, from near the southern city of Cusco.

"We want to be moved and we want justice. We want to be heard - because we never have been," she added.

Filomeno Aylas, from La Oroya in central Peru, a desperately polluted Peruvian refinery town where people have shown blood lead content close to biological tolerance levels, said children as young as three were showing lead in their blood. "It's a calamity," he said.