Dave Thomas and several other Canadian actors said Tuesday they support a protest planned by Greenpeace in Ottawa against the oilsands industry.

Greenpeace said it hopes to muster hundreds of protesters Monday in front of the Centennial Flame on Parliament Hill. The protest would follow similar demonstrations in Washington, D.C., in August and coincide with nine hearings by the U.S. State Department over the next two weeks.

Those are scheduled for Washington and in states along the route of the Keystone XL pipeline proposed by Calgary-based TransCanada.

It  would ship oilsands crude from Alberta to refineries in the U.S.

The hearings will help determine whether the Obama administration will grant a permit for the 2,700-kilometre pipeline by the end of the year.

Thomas, of SCTV fame, said he opposes the pipeline.

Thomas, perhaps best known for portraying beer-drinking lout Doug McKenzie, said the pipeline would be an environmental disaster and that it must be stopped.

Oil lobby says pipeline would create jobs

Other Canadian actors who said they support the planned sit-in include Graham Greene, Mia Kirshner and Kate Vernon. It is not clear which, if any, of the actors will actually attend the demonstration.

Greenpeace opposes development of the oilsands, saying it contributes to global warming. It also says the pipeline poses the risk of a spill that would contaminate the Ogallala Aquifer, the main source of fresh water for the Great Plains.

Concern for the fragile Nebraska Sandhills, which lie above the aquifer, has led Nebraska Gov. Dave Heineman to call for rejection of the pipeline in its current route.

TransCanada has said a study shows that alternatives to the proposed route would be longer, disturb more land and cross more water bodies.

Also Tuesday, the lobby for big U.S. oil, the American Petroleum Institute, called for the White House to support the project as "one of the shovel-ready projects the president considers as part of his jobs program."

API cited a study by Calgary-based Canadian Energy Research Institute that increased investment in Canadian oilsands development will contribute $775 billion US to the American economy and create more than 500,000 new American jobs by 2035.

Nearly 2,400 American companies in 49 states are already involved in the development of Canada's oilsands, API said,  by supporting U.S. infrastructure or Canadian development projects.

With files from The Canadian Press