Foreign Minister Bill Graham said it would be a "bad mistake" which could lead to long term problems.

"The big red line we all have is the weaponisation of outer space, which I believe would be immoral, illegal and a bad mistake," Graham said in an interview with the Globe and Mail newspaper released Wednesday.

"There are voices in Washington that are calling for that and we are strongly urging them this would be an extremely unfortunate development for peace," he added.

US President George W. Bush has said the plan would begin with the deployment of ground-based and sea-based interceptor missiles, Patriot missiles, and sensors based on land, at sea and in space, all devoted to the task of shooting down incoming enemy missiles.

"The fact of the matter is they will have established the principle (of space weapons) and they can't guarantee they'll have the technological superiority 25 years from now and that's going to be a problem for everybody," Graham warned.

According to the Defense Department the initial plan is for 10 ground-based interceptor missiles to be based in Alaska in 2004, and another 10 in Alaska and California by 2006.

But analysts here said while Canada may oppose the initiative politically, militarily it might not have much choice but to support the action.

"In 12 to 24 months the Americans are going to ask us: are you in or not? And at that point, if Canada says no, it will be marginalized," said Jean-Philippe Racicot, strategic affairs researcher at the University of Quebec at Montreal.

"So despite the official protests, we're not going to have any choice but to go along."

Ottawa could do little to stop the United States, concluded Louis Balthazar, interim head of the same university's strategic studies department.

"Canada is so closely tied to the United States, it would be difficult to bypass this project," he said, noting that the first set of interceptors are to be deployed in Alaska, "not too far from us".