Defence Minister David Pratt says although Canada remains opposed to the weaponization of space, Ottawa plans to continue discussions with Washington on a proposed missile defence shield.

Speaking to CTV's Question Period on Sunday, Pratt said critics of Canada's involvement -- notably the NDP and the Bloc Quebecois -- are opposed to the potential of weapons in space, which aren't part of the current program.

"It's important not to get too far ahead of ourselves in terms of speculation," Pratt said. "What the NDP and the Bloc have been talking about is what they think this missile defence system is going to become in the years ahead, well into the future. What the government is saying is, let's deal with what it is now."

Pratt said the current proposal includes "a limited system of land- and sea-based interceptors to protect North America."

He said no decision has been made as to whether U.S. missile launchers would be based in the Canadian north.

"We're not saying no, we're not saying yes," Pratt said, adding that the U.S. already has its own northern base at Fort Greeley in Alaska.

The multi-billion-dollar missile defence shield is intended to shoot down missiles fired by rogue states and to thwart accidental launches. It is designed to monitor an area up to 320 kilometres beyond the horizon, far more than the 50 km that ordinary radar covers.

Opponents maintain the shield will evolve into a return to the 'Star Wars' plan that emerged during the Reagan years, leading to a new arms race.

But Pratt was adamant that Ottawa does not seek such a goal.

"Our objective should be to keep weapons out of space, there's no question about that" he said. "This is not about a new arms race at all."

Pratt also noted that since 1996, the United States has a policy against the weaponization of space.

"That is the policy that they're following right now but it allows for research and development in those areas," he said.

The Canadian Department of National Defence has issued $700,000 in contracts to test Canadian radar technology at U.S.-run missile defence trials.

Last week, Pratt denied that the contracts meant Canada's participation is a foregone conclusion.

Pratt said Washington has been "flexible" in talks with Ottawa and has imposed no deadlines for Canada to join.

Washington's goal is to have the first handful of missiles and their accompanying radar sites operational by October.