In the wake of the U.S. imposing new penalties on Canadian softwood lumber imports, B.C. Premier Christy Clark is asking Ottawa to ban the shipment of all thermal coal — including U.S. thermal coal — through British Columbia.

"We've gone from seeing Americans as being good trading partners to being hostile trading partners," said Clark when asked why she was making this move now.

On Monday, the U.S. Department of Commerce announced its first batch of duties on Canadian softwood lumber imports, ranging from three to 24 per cent, a move that could have serious consequences for B.C.'s large forestry industry.

Westshore Terminals in Delta receives a coal shipment. (WCWC)

Clark said the coal transport ban is something her government had been considering for a while.

"Now that softwood negotiations are at an impasse...we are free to make this change," she said.

"Dirty thermal coal is terrible for the environment. It acidifies our oceans, it speeds up climate change... We're in a unique position to stop that."

In a letter to Prime Minister Justin Trudeau Clark says,"For years, American thermal coal exports through Canada have been increasing due to a shortage of U.S. port capacity."

"By eliminating thermal coal shipments from British Columbia ports, we can open up additional capacity for metallurgical coal that is used to make long-lasting steel, not burned to produce short-term electricity."

Stock prices take a hit

Vancouver's Westshore Terminals, a major exporter of thermal coal, saw its stock price drop almost 12 per cent Wednesday following the announcement.

Westshore's investors include bcIMC, the province's investment management company, which holds $6 million in Westshore stock.