Prime Minister Stephen Harper has not ruled out extending Canada's military involvement in Afghanistan beyond the 2014 withdrawal of NATO forces.

Under questioning from Opposition Leader Thomas Mulcair in the House of Commons Wednesday, Harper said Ottawa will "examine all options" if asked to leave a contingent of special forces in the war-ravaged country after spring 2014.

According to a media report, the U.S. has asked Canada and Australia to keep some of their troops in Afghanistan to help American forces capture Taliban and al Qaeda insurgents and train Afghan soldiers.

But Harper said Canada has received no "specific" request from the U.S. to stay on past 2014.

"As we approach that date, we will examine all options and we will take the decision that is in the best interest of this country and in the best interest of our security objectives for the globe," Harper said during question period.

His comments outraged Mulcair, who said the NDP won't support any extensions and Canadian forces must pull out as planned.

Keeping troops in Afghanistan past 2014 would be a violation of a parliamentary motion that ended Canada's combat mission in Kandahar last year, the NDP said.

Canada's special forces have been operating in the country, alongside U.S. troops, since 2001. As with the regular army, their combat mission ended last summer, but a small contingent is still part of NATO's training efforts in Kabul.

Mulcair pressed Harper on the issue Wednesday, saying Canada's mission in Afghanistan has been extended multiple times since 2006.

"When will it finally end?" Mulcair asked.

Harper responded by saying that Ottawa will not make its decisions based on an "ideological, knee-jerk response by the NDP."

Speaking on CTV's Power Play Wednesday, University of Ottawa international affairs professor Philippe Lagasse said there will likely be "a lot of pushback" from opposition parties and Canadians if the Conservatives decide to reopen the Afghanistan issue in the House of Commons.

A request to continue providing military support in the country will also likely be made at a future NATO summit, Lagasse said.

"There is going to be an enormous amount of pressure on the Harper government to continue this," he said. "Now whether or not it's a good thing is a whole other debate."

Renee Filiatrault, a former political aide who served with the Kandahar Task Force as a civilian, told Power Play that keeping special forces in Afghanistan "can be a very good thing."

"I think it's a niche capability that Canada is extremely good at," she said.

Lagasse, however, said that special forces' operations are secretive by nature and may not be welcomed by Afghan citizens and soldiers.

"It's going to be a lingering question of what exactly these forces are doing, how they're being used and if they are effective," Lagasse said.

But Filiatrault said that Canadian soldiers have proven to be sensitive to Afghans' culture and customs over the years. While special forces are usually associated with "capture and kill" missions, they can perform a number of different roles, including military training, she said.

While NATO allies are concerned that Afghan forces won't be able to handle security threats when foreign troops leave, interim Liberal Leader Bob Rae said it's time to "take off the training wheels."

"I think anybody looking at the situation in Afghanistan would say clearly, the government of Afghanistan simply has to step up to take on its responsibilities," he said.

With files from The Canadian Press