VANCOUVER -- A coalition of First Nations and conservation groups is suing the Yukon government over its decision to open a vast region of the Canadian North to mining and industrial development.

The group says the decision ignores a land-use plan seven years in the making.

A lawsuit was filed Monday in Yukon Supreme Court by the Nacho Nyak Dun, the Tr'ondek Hwech'in, the Canadian Parks and Wilderness Society Yukon and the Yukon Conservation Society.

They say the plan released a week ago in Whitehorse violates the land-use planning provisions of a land claims agreement the territory signed with First Nations.

"It's a lawsuit that nobody wanted to bring," said their lawyer Thomas Berger, who headed the landmark Mackenzie Valley Pipeline Commission in the territory almost 37 years ago.

"But the government of Yukon has forced these plaintiffs ... to go to court not only in defence of First Nations rights and environmental values in Yukon, but also to uphold principles entrenched in the Constitution."

Berger said the development plan announced last Monday discards years of work by the planning commission and ignores the views of First Nations and the affected communities.

"No matter how it is viewed, it is a complete rewrite ...," he said at a news conference in Vancouver to announce the legal action.

Under the commission's land use plan released in 2011, 55 per cent of the watershed in northeastern Yukon would have been protected.

Instead, the government plan protects 29 per cent of the area, though existing mineral claims within that zone can still be developed. Another 44 per cent of the watershed is open to restricted use and 27 per cent open to most land use activities and development.

"This remote area holds resources that have the potential to be of great value to Yukon's economy, both now and in the future," Yukon Minister of Energy, Mines and Resources Scott Kent said in a statement when the plan was released.

"The plan recognizes existing mineral interests and accommodates future exploration, while giving the Yukon government the tools to manage the footprint of any new development and to protect ecological, cultural and wilderness values."

The Peel watershed encompasses the Peel, Ogilvie, Blackstone, Hart, Wind, Snake and Bonnet Plume rivers in Yukon, and drains into the Mackenzie River basin in the Northwest Territories.

The lawsuit says a territorial government cannot unilaterally disregard the planning commission recommendations, and asks the court to compel the government to implement the plan released in 2011.

"The Yukon government has betrayed the public trust," said Karen Baltgailis, executive director of the Yukon Conservation Society.

Chief Ed Champion of the Nacho Nyak Dun First Nation said his community is not against mining and development.

"We have lived closely with mining for over 100 years. Many of my people are miners or work in the mining industry. We have excellent relationships with mining companies that we work hard to maintain," Champion said.

"That said, we do not want to see mining in the Peel watershed. To us, that land and water is sacred and should be preserved for future generations."

The government's decision created uncertainty for mining and industrial developers, as well, the groups said.

Baltgailis called on the companies with thousands of mining claims in the area the commission recommended be protected -- citing Chevron specifically -- to "show real corporate citizenship" and voluntarily relinquish those claims.

"The social capital that companies would receive by making this timely and vital contribution to conservation would far outweigh any economic value that these remote and inaccessible mining claims may have," she said.

A coalition of First Nations and conservation groups is suing the Yukon government over its decision to open a vast region of the Canadian North to mining and industrial development.

The group says the decision ignores a land-use plan seven years in the making.

A lawsuit was filed Monday in Yukon Supreme Court by the Nacho Nyak Dun, the Tr'ondek Hwech'in, the Canadian Parks and Wilderness Society Yukon and the Yukon Conservation Society.

They say the plan released a week ago in Whitehorse violates the land-use planning provisions of a land claims agreement the territory signed with First Nations.

"It's a lawsuit that nobody wanted to bring," said their lawyer Thomas Berger, who headed the landmark Mackenzie Valley Pipeline Commission in the territory almost 37 years ago.

"But the government of Yukon has forced these plaintiffs ... to go to court not only in defence of First Nations rights and environmental values in Yukon, but also to uphold principles entrenched in the Constitution."

Berger said the development plan announced last Monday discards years of work by the planning commission and ignores the views of First Nations and the affected communities.

"No matter how it is viewed, it is a complete rewrite ...," he said at a news conference in Vancouver to announce the legal action.

Under the commission's land use plan released in 2011, 55 per cent of the watershed in northeastern Yukon would have been protected.

Instead, the government plan protects 29 per cent of the area, though existing mineral claims within that zone can still be developed. Another 44 per cent of the watershed is open to restricted use and 27 per cent open to most land use activities and development.

"This remote area holds resources that have the potential to be of great value to Yukon's economy, both now and in the future," Yukon Minister of Energy, Mines and Resources Scott Kent said in a statement when the plan was released.

"The plan recognizes existing mineral interests and accommodates future exploration, while giving the Yukon government the tools to manage the footprint of any new development and to protect ecological, cultural and wilderness values."

The Peel watershed encompasses the Peel, Ogilvie, Blackstone, Hart, Wind, Snake and Bonnet Plume rivers in Yukon, and drains into the Mackenzie River basin in the Northwest Territories.

The lawsuit says a territorial government cannot unilaterally disregard the planning commission recommendations, and asks the court to compel the government to implement the plan released in 2011.

"The Yukon government has betrayed the public trust," said Karen Baltgailis, executive director of the Yukon Conservation Society.

Chief Ed Champion of the Nacho Nyak Dun First Nation said his community is not against mining and development.

"We have lived closely with mining for over 100 years. Many of my people are miners or work in the mining industry. We have excellent relationships with mining companies that we work hard to maintain," Champion said.

"That said, we do not want to see mining in the Peel watershed. To us, that land and water is sacred and should be preserved for future generations."

The government's decision created uncertainty for mining and industrial developers, as well, the groups said.

Baltgailis called on the companies with thousands of mining claims in the area the commission recommended be protected -- citing Chevron specifically -- to "show real corporate citizenship" and voluntarily relinquish those claims.

"The social capital that companies would receive by making this timely and vital contribution to conservation would far outweigh any economic value that these remote and inaccessible mining claims may have," she said.

Meanwhile, the Yukon government said Monday that it is boosting the amount of money available to assist the mineral exploration industry.

Funding for the Yukon Mineral Exploration Program is being increased by $630,000 this season to a total of $1.4 million, subject to legislative approval.

The program helps individuals, partnerships and junior mining companies move forward on their exploration projects.

"This investment has a track record of succeeding," said Premier Darrell Pasloski in Vancouver while attending the Mineral Exploration Roundup.

"We have also seen that the program provides incentive for companies to operate locally and invest in Yukon's economy."

Last season, 55 Yukon exploration projects were funded through the program, which was half of the total number of active projects in the territory.