A gold and silver mine in Mexico owned by the Vancouver-based company Fortuna Silver — and the death of a prominent activist opposed to the operation — were the focus of a three-day international observation mission this past week.

Observers travelled to San José del Progreso in Oaxaca province, where the company began production in September 2011, to investigate the violence that many say appears related to opposition to the mine and its impact on the local water supply.

The mission, led by the Council of Canadians and Blue Planet Project, met with community members for and against the controversial Fortuna Silver mine, as well as representatives from the Canadian company's local subsidiary, Minera Cuzcatlán.

Two anti-mine activists from the town were killed by gunfire earlier this year and three others injured. Those killed included the outspoken leader of the opposition campaign, Bernardo Vásquez Sánchez.

Residents say the mine has polarized the community. There are reports Vásquez had received death threats in the weeks before he was gunned down in his car last March.

Fortuna Silver executives say the violence in San José del Progreso is the result of social divisions that existed before the company arrived.

Meera Karunananthan with the Council of Canadians says the situation in San Jose del Progreso is not entirely a local problem.

"This is part of an international pattern with Canadian mining companies violating human rights in communities abroad," she said.

Members of communities affected by Canadian-owned mining projects have held protests outside the Canadian Embassy in Mexico City.

Karunananthan says these communities have no legal recourse within Canada.

"Mining communities benefit from an environment where communities are struggling to have their human rights recognized and established in courts. But they're also benefitting from an international environment where investor rights are recognized within international trade agreements."

A bill known as C-300, which would have given the Canadian government the authority to investigate complaints of wrongdoing and withhold public funds from Canadian companies operating abroad was defeated in 2010 by a margin of six votes.

A similar bill, C-323, is currently making its way through Parliament.