People in the UK are being urged to support a legal fight by a Canadian Cree community against "tar sands" – a form of fossil fuel which campaigners warn could help push the world into a climate disaster.
The Co-operative Financial Services is backing the Beaver Lake Cree Nation, who are fighting the extraction of tar sands from their ancestral lands in the boreal forest of Alberta because of the damage it is doing to their environment.
The Beaver Lake Cree claim the strip mining, drilling for oil and prospecting for fuels through the forest is harming human health and wildlife and polluting rivers, lakes and water supplies.
They say it is also preventing them from hunting, fishing and gathering plants – rights enshrined in a 19th-century treaty and now part of the Canadian constitution.
The Co-operative is backing their legal battle as it believes it is the "one of the last and best hopes" to stop new tar sands developments, which use far more energy to produce oil than conventional fossil fuels.
A charitable trust fund has been launched to allow people to give money to support the Cree's legal fight, with the financial group donating £53,000 to the cause.
The donation follows £50,000 given by the Co-operative to help record the testimony of Cree elders for the case about the damage being done to their environment.
Tar sands are a mixture of sand or clay and bitumen, which are either pumped from underground using steam or dug out in strip mines and which need pre-processing or "upgrading" before they can be refined. Shell is among the companies developing tar sands in Alberta, despite its extraction project losing $42m (£25.4m) in the first three months.
Campaigners say the process of extracting tar sands produces an average of three times the carbon emissions of conventional oil production.
A study last year by WWF and the Co-operative warned that the extraction of all the unconventional fossil fuels in North America would produce enough emissions to push atmospheric carbon dioxide levels well past the point at which dangerous climate change would occur.
But tar sands are big business in Canada, where multi-national oil companies are rushing to exploit the estimated 315bn barrels thought to be under the ground, developing huge areas of the wilderness for extraction.
The Cree, who gave up ancestral lands almost as big as England and Scotland put together in return for the guaranteed right to hunt, fish and gather plants in the territory, say people's health is suffering as the result of local pollution.
Toxic lakes of water used in the extraction process are harming wildlife, the fish and animals they hunt are unhealthy and moose and caribou populations have been hit as a result of lines clear-cut through the forest for seismic prospecting for oil.
The deer will not cross the "seismic lines", which wolves exploit for hunting, and have also found their movement hampered as a result of hundreds of miles of pipelines through the forest and breeding grounds disturbed, the Cree say.
Chief of the Beaver Lake Cree, Al Lameman, said: "We are facing powerful and wealthy opposition, but we remain firm in our resolve to protect these lands from destruction."
He added: "Our fight is your fight."
Paul Monaghan, head of social goals and sustainability at the Co-operative, said the Beaver Lake Cree's legal fight was bigger than lawsuits against "big tobacco" or Erin Brockovich's battles against pollution.
"The Beaver Lake Cree's legal case maybe one of the last and best hopes to stop new tar sands development.
"This small group of indigenous people are taking on not just the governments of Canada and Alberta, but some of the biggest companies in the world.
"They have the support of Canada's leading lawyer on aboriginal law, who has a track record of winning such cases. But they are going to need financial support – and lots of it."
Costs for the case, which is expected to take several years to come to court, is likely to run to millions of dollars.