A Vancouverbased mining company's plans to build a silver mine in southeastern Peru have triggered violent opposition.

Protesters in the Peruvian city of Puno opposed to a silver mine proposed by Bear Creek Mining Corp. blocked area transportation on Friday, one day after mobs stormed two government offices.

The protesters, mostly Aymara Indians, are angry that the central government granted Bear Creek a concession to open a silver mine in the community of Santa Ana 140 kilometres south of Puno.

Residents fear the mine will pollute the water and leave few local benefits.

Some 15,000 protesters were blocking the main roads, the airport and the rail line. Hundreds of foreign tourists are trapped in the city, located on the shores of Lake Titicaca -the highest navigable lake in the world, shared between Peru and Bolivia.

The demonstrations began more than two weeks ago but radicalized Tuesday when protesters blocked all routes of access to the city of 120,000.

The protest turned violent on Thursday when some 400 protesters stormed two government office after talks between local leaders and representatives of the government of outgoing President Alan Garcia collapsed.

"We are going to defend our lands to the final consequences, even though the government is increasing pressure by bringing in soldiers and police," said protest leader Hernan Cauna.

Despite the violence there were no clashes with police, said the head of local police, General Wilmar Andia.

Thousands of peasants flocked to Puno from the surrounding area for the protests and were staying at a local sports stadium.

The government is unlikely to crack down on the protesters until after the June 5 presidential run-off vote between conservative Keiko Fujimori, the daughter of jailed ex-president Alberto Fujimori, and leftist-nationalist Ollanta Humala.

In a feasibility study done for its Santa Ana silver project, Bear Creek said a mine would have capital costs of $70.8 million US, enjoy an 11-year life and produce 47.4 million ounces of silver.