Pipeline planner TransCanada can expect to face "considerable opposition" to its Energy East tar sands pipeline for the eastern Canada, an advocacy group said.

TransCanada submitted a formal permit to move ahead with its Energy East pipeline. The project would add new pipeline and convert existing gas infrastructure to carry Alberta oil to the eastern Canadian market.

Advocates with the Natural Resources Defense Council's International Program said the project puts the eastern Canadian shoreline at risk.

"A new tar sands pipeline called Energy East proposed by TransCanada -- the company behind the contentious Keystone XL tar sands pipeline -- faces considerable opposition and numerous hurdles that make this project far from a done deal," they said in a Thursday statement.

TransCanada says Energy East would give refineries a source of domestic crude in a market otherwise dependent on foreign suppliers. Critics have countered the oil sent from Energy East is meant for exports.

The company said the $12 billion pipeline is good for Canadian energy security.

"It will provide the safest and most efficient access to markets for Canada's growing crude oil production, ensuring we realize the greatest value for our natural resources," TransCanada President and Chief Executive Officer Russ Girling said in a statement.