The federal government's backup plan in the event of a catastrophic oil spill in British Columbia's waters relies on using chemical dispersants that are currently banned from marine use by the Department of Fisheries and Oceans.

B.C. Environment Minister Mary Polak says her province is not prepared to sign off on the federal oil-tanker safety plan rolled out last month as part of an effort to address concerns about marine environmental safety in advance of Ottawa's Enbridge Northern Gateway pipeline decision.

The federal Conservative government is expected to announce this week whether the pipeline can go ahead, a decision anxiously anticipated by environmental and aboriginal groups who maintain a spill from tankers carrying the oil delivered by the pipeline will cause long-lasting cultural and environmental devastation.

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Far from addressing the province's demands for better spill response, the federal proposal could push the B.C. government further away from endorsing new oil pipelines.

In an interview, Ms. Polak says her officials are seeking details from Ottawa about what the new guidelines would look like. If B.C. isn't convinced that the proposed solution meets its demands for "world-leading" oil-spill safety, she said the province is prepared to deny pipeline permits.

"If there are significant adverse environmental effects, then we don't approve those permits."

Currently, the use of spill-treating agents such as Corexit, which was widely used in the Deepwater Horizon oil spill in the Gulf of Mexico four years ago, are effectively prohibited in Canada.

Corexit is not banned by name but using it or other spill-treating agents could violate a number of laws including the Fisheries Act, which outlaws the deposit of deleterious substances in waters frequented by fish.

Ottawa would also have to amend the Shipping Act and the Environmental Protection Act to allow the use of alternative response measures, including chemical dispersants and burning spilled oil, for a marine spill.

The measures would only be approved if they were determined to have a net environmental benefit, Environment Canada officials said.In British Columbia, the Environmental Management Act threatens penalties for introducing chemical dispersants into the environment. Ms. Polak said there are no plans to change that law.

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"If it was going to happen, it would have to be under guidelines that our experts can accept as being appropriate," Ms. Polak said in an interview.

On Monday, First Nations leaders, oil company executives and politicians will meet in Vancouver to discuss marine safety and oil tankers. Greg Rickford, federal Minister of Natural Resources, will be there to explain why Ottawa's tanker safety plan should soothe British Columbians' fears about increasing oil tanker traffic.

Art Sterritt, executive director of the Coastal First Nations, will be there to tell Mr. Rickford that his community will block the use of chemical dispersants.

Mr. Sterritt travelled to the Gulf of Mexico during the cleanup of the Deepwater Horizon spill in the spring of 2010. On a sandy white beach in Pensacola, Fla., cleanup crews would spray his shoes with Corexit to remove the sticky tar balls. "They were cleaning up what showed up on the beaches but they weren't able to clean up in the water," he said. In addition to the oil, the chemical residue from the dispersant continues to affect marine life in the Gulf of Mexico.

"That gave us serious pause about decisions that Coastal First Nations would make with respect to Northern Gateway," he said. "The reality is, it is even more damaging than the product they are trying to cover up. It's pretty scary."