At his first Quebec appearance since two Quebec-based soldiers died in Afghanistan, Prime Minister Stephen Harper nearly completely refrained from commenting on the mission in the war-ravaged country.

In a wide-ranging, 20-minute speech in Victoriaville on Sunday, Harper had just one paragraph for the military.

"When men and women volunteer and find themselves in dangerous places to defend our values and our way of life, we thank, from the bottom of our hearts, these men and women who wear the uniform for the peace, freedom and prosperity that their efforts allow us to enjoy," he said in French, adding that Conservatives weren't ashamed of "Canada's rich military heritage."

Later that afternoon, a Canadian Forces aircraft touched down at CFB Trenton in eastern Ontario, returning the remains of Master Warrant Officer Mario Mercier and Master Cpl. Christian Duchesne to Canadian soil.

They died Wednesday, along with an Afghan interpreter, when their vehicle struck a roadside bomb. Two Radio Canada journalists were in the vehicle. One was injured, along with another soldier.

Harper, who didn't use the word "Afghanistan" in the speech, wouldn't answer reporters' questions afterwards.

Officials from the Prime Minister's Office say Harper refuses to play politics with the deaths of soldiers.

The two soldiers returned to Canada on Sunday and a third -- Pte. Simon Longtin, 23, to be buried Monday -- all served with the Royal 22nd Regiment, based at CFB Valcartier in Quebec.

Public opinion polling has found opposition to the Afghanistan mission to be highest in Quebec.

Harper has called three Quebec byelections for Sept. 17. His Sunday speech was delivered to party supporters. All three byelection candidates were there.

Some of the Conservatives' opponents have said they may use those byelections as referendums on the Afghanistan mission.

Earlier this month, Harper shuffled his cabinet. He placed Quebec MP Maxime Bernier in the foreign affairs portfolio and Nova Scotia MP Peter MacKay in the defence portfolio in a move many saw as an attempt to improve communications about the Afghanistan mission -- particularly in Quebec.

On CTV's Question Period, a former federal Liberal politician said there's been silence in Quebec so far from the Tories.

"People have never heard them," Jean LaPierre said of Bernier and MacKay. "So now it's time for them now to go on a speaking tour and explain the mission because as of now, they haven't talked since the day of their swearing-in."

Also speaking on Question Period, Liberal Leader Stephane Dion continued to push the Conservatives to commit Canada to withdrawing its troops from a combat role in Afghanistan by February 2009.

On Sunday, Bloc Quebecois Leader Gilles Duceppe issued a statement responding to remarks Saturday by Sen. Michael Fortier, the government's public works minister, who said Duceppe had only spoken up about the Afghanistan mission in recent days because Quebec troops had died.

Duceppe, who called Thursday for an emergency debate when Parliament resumes on Sept. 17, called Fortier's comments "baseless" and in "bad taste."

The Bloc caucus is "saddened by the deaths of all Canadian soldiers, Stephen Harper knows that," he said.

In his speech Sunday, Harper referred to the previous Liberal government as corrupt and called the Bloc, the most popular political party in Quebec, impotent.

With a report from CTV's David Akin and files from The Canadian Press