Canada's approval last week of an oil export project that could also create a seven-fold increase in tanker transits is drawing scrutiny from a US senator concerned about potential oil spills.

Maria Cantwell, a Democrat from Washington state, sent a letter to President Obama and US Coast Guard Commandant Paul Zukunft with regard to the Trans Mountain Pipeline.

Canada's Prime Minister Justin Trudeau signed off on the Kinder Morgan-backed project, which will triple the volume of crude oil carried from Canada's oil producing province of Alberta to British Columbia.

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