American officials are wading into the debate over the expansion of Kinder Morgan's Trans Mountain oil pipeline in British Columbia.

The U.S. Coast Guard is voicing its concern about Kinder Morgan’s Trans Mountain pipeline expansion, and will now try to determine whether the $4.3-billion project will have a negative impact south of the border.

Kinder Morgan has plans to more than double the pipeline's capacity, meaning tanker traffic will increase around 300 per cent.

“A spill in a heavily populated area or in the waters in the strait of Juan de Fuca could cause billions of dollars in damage, and harm businesses throughout the region,” Washington state Sen. Maria Cantwell said in a speech to the U.S. senate.

"The response can't be even if the spill happens in Canadian waters, don't worry, just call the Americans."

A legislative amendment proposed by Cantwell and signed into law by U.S. President Barack Obama a couple of weeks ago gives the U.S. Coast Guard six months to conduct a risk assessment of the planned expansion of oil pipeline capacity to the West Coast.

Burnaby Coun. Sav Dhaliwal said the city supports the current pipeline, which has been around for close to 60 years, but does not back Kinder Morgan’s plan to increase its output.

“We have people living within 500 metres of the tanks now, and the pipeline goes right through the neighbourhoods of established communities,” he said.

“It only takes one spill of that to change the whole ecology and environment.”

Dhaliwal said the City of Burnaby is calling on the provincial and federal governments to join the U.S. in taking a closer look at the proposed plan.

“Who’s looking after the ecology, who’s looking after people who live here, and that should have been the people of British Columbia,” he said. “Instead, it’s the United States.”

Calls to Kinder Morgan seeking comment Monday were not returned.

A spokesman for Canada's federal Transport Minister Denis Lebel said the U.S. and Canada are constantly working together to try and ensure the safe and secure transportation of natural resources across their shared border.

"Our government has been clear: If any project does not meet or surpass our stringent environmental standards, it will not proceed," spokesman James Kelly said in an email.

"Canada has already strengthened our strong record of environmental protection by requiring double-hulled tankers, mandatory pilotage and increasing navigational toolsand–and that work continues."

The Coast Guard will study the risk of transporting oil via supertanker, tanker and barge through the Salish Sea waterways, which encompasses U.S. and Canadian territorial waters between southern Vancouver Island and the mainland. It includes Juan de Fuca Strait, the Strait of Georgia, Haro and Rosario Straits and Puget Sound.

The commandant of the U.S. Coast Guard must submit recommendations to the House of Representatives' transport committee by the end of June.

In operation since 1953, the Trans Mountain pipeline runs from just outside Edmonton to Burnaby. From there the oil is distributed through separate pipelines to local terminals, a refinery and the Westridge marine terminal in Port Metro Vancouver.

With files from CTV British Columbia's Scott Hurst and The Canadian Press