CALGARY (Reuters) - Native chiefs in the Western Canadian province of British Columbia voted on Wednesday to join some of their eastern counterparts opposed to a major pipeline project, in a move some leaders described as a step toward a national alliance aimed at blocking expansion of Alberta’s oil sands industry.

The chiefs from British Columbia agreed to join opposition to the Energy East project - proposed by TransCanada Corp at the meeting, also attended by chiefs from the Canadian provinces of Ontario, Manitoba and Quebec. If approved, the Energy East pipeline would carry up to 1.1 million barrels of crude oil per day from Alberta’s oil sands to the Atlantic coast, along a 4,200 km (2,850-mile) route.

Canada’s oil sands in northern Alberta are home to the world’s third-largest crude reserves but they also represent the country’s fastest growing source of greenhouse gas emissions due to their energy intensive production methods. While the industry has said it needs to expand pipelines to give it access to new markets and promote responsible expansion, environmental and aboriginal groups and some municipalities across the country have opposed new projects, due to the risk of spills and the climate change impacts.

The native leaders also released a draft national treaty at the meeting, to be circulated among First Nations across the country, that would call for them to prohibit, challenge and resist use -whether by pipeline, rail or tankers - of their territories for expansion of oil sands production.

Some British Columbia First Nations have opposed pipeline expansion projects proposed to the Pacific coast from Alberta.

“So I think that governments need to take notice that our groups are organizing in a very serious way and forming formal alliances that will amplify our voices,” said Stewart Phillip, grand chief of the union in British Columbia, which represents more than half of the First Nations communities in the province.

When asked about the vote, TransCanada spokesman Tim Duboyce said the company has taken comprehensive steps to consult with First Nations, and wants to hear their concerns to improve the Energy East project.

Serge Simon, chief of the Quebec Mohawk community of Kanesatake, near Montreal, said the proposed alliance of First Nations would be designed to ensure that aboriginal leaders are aware of their right to oppose projects on their territory.

The ruling Conservative party, now in the middle of a tight three-way election race with the opposition New Democrats and Liberals, has supported pipeline expansion, saying it is taking a responsible approach to development, while protecting the environment.