Opposition leaders expressed serious misgivings about Canada's Afghanistan mission on Wednesday, after reports emerged that six soldiers had died in a roadside bomb explosion.

"The prime minister has said that he needs to have a consensus in order to extend the mission beyond February of 2009," said Liberal Leader Stephane Dion. "This consensus will never exist.

"You know what is the views of the other parties and what is the view of the official Opposition. So the prime minister should say that right away.

"It should have been done weeks ago."

In an earlier press conference, NDP Leader Jack Layton urged Prime Minister Stephen Harper to do what Canada is best known for -- initiating a peace process that will not only help stabilize the region but will also help scale back the military operations in Afghanistan.

"A comprehensive peace process must include all combatants, all elements, all countries involved in the region with international leadership," Layton said in Ottawa.

"Canada is an expert in this area. We used to be known globally for our expertise in this area. I believe it's time for Canada to get back on that path and begin to carve out with those many nations who are concerned about what is happening in Afghanistan, and Afghan leadership, to adopt a new strategy."

Since 2002, 66 Canadian military personnel have lost their lives in Afghanistan, along with one diplomat.

The six Canadian soldiers who died Wednesday were killed by a roadside bomb 20 kilometres from Kandahar. They were traveling in a RG-31 Nyala armoured vehicle with an Afghan interpreter when they were hit. The interpreter was also killed.

Retired Maj.-Gen. Lewis MacKenzie said that casualties must be accepted if Canada believes in the importance of the Afghanistan mission.

But he added that unless NATO offers Canada more support in southern Afghanistan, the chaotic region where Canadian troops have endured much of the fighting, then the mission should not be extended.

"If NATO doesn't get off its butt and countries that aren't participating don't start showing up in numbers, and start increasing the number of troops in the south ... then I won't be at the head of the line in 2009 saying we should stay," he told CTV Newsnet.

Layton said Canada should not be focusing on military operations at all, because the fighting is only fueling Taliban support and civilians are paying for it. So far, 270 Afghan civilians have been killed during the military operations.

If Canada doesn't start implementing peace instead, Canadians could be stuck in an extended role in Afghanistan that is escalating day by day, he continued.

"What is happening now is working for the Taliban, not against them," he said. "In other words, we're seeing growth of support of the Taliban because of these airstrikes, the escalation of war and the death of civilians. That's why comprehensive peace process involving all of the countries, involving all of the players has got to be initiated."

The Afghan mission will be a priority issue for the NDP in the next federal election, Layton promised.

"Any time Canadian soldiers are killed, Canadians are thinking of their families and comrades and supporting our troops," said Layton when asked about the latest casualties.

"This simply underlines, with this escalating death toll of the soldiers and of civilians in Afghanistan, that this mission is going in the wrong way."

With a report by The Canadian Press