Canadian special forces have returned fire against the Islamic State in Iraq and Syria (ISIS) a total of three times, Capt. Paul Forget from Canadian Joint Operations Command said in Ottawa on Monday.

Brig.-Gen. Michael Rouleau, commander of the Canadian special operations forces command, said last Monday the forces had come under "immediate and effective mortar fire" and responded with sniper fire, "neutralizing the mortar and the machine-gun position."​

"Two similar events have occurred over the last week and in both cases Canadian special operation forces, again acting in self-defence, effectively returned fire, neutralizing the threat," Forget said today.

Asked whether the involvement of special forces in firefights was becoming the norm, Forget said the role of Canadian troops was evolving, but that they are conducting operations within their mandate.

"I don't think I would characterize that as the new norm, but rather as more of a — a bit of a state of evolution of our role in the advise and assist capacity," he said.

Forget said that Canadian troops have moved beyond teaching Iraqi forces "the basics of warfare."

"That has since evolved somewhat to the point where we're now able to get into a little bit more of a tactical battlefield … type of atmosphere."

"As part of the evolution of the conflict … that's happening in the area where our special operations forces are conducting the advise and assist role, they're conducting those operations within the mandate that was assigned to them," Forget said.

He said the special forces were acting in self-defence and there were no injuries to Canadian soldiers.

In response to a question from CBC News Monday, a spokeswoman for the Combined Joint Task Force, which is co-ordinating the international coalition's mission in Iraq, said, "Canada is the only coalition member whose soldiers have been involved in firefights."

"All members of the coalition retain the right to self-defence and will take appropriate actions in response to identified threats," Maj. Neysa N. Williams added.

The Pentagon told CBC News that no U.S. personnel have engaged in firefights with ISIS on the ground.

Last November, Britain's the Mail on Sunday, citing sources, reported that the U.K.'s elite SAS troops, who were officially in Iraq in a reconnaissance role, were conducting raids against ISIS fighters.

Opposition leaders, Nicholson spar over mission

The opposition New Democrats and the Liberals pounced on the government last week, accusing the Conservatives of misleading Parliament after it was revealed that Canadian special forces had exchanged gunfire with ISIS.

Today, NDP Leader Tom Mulcair led off question period by asking the Conservatives about the nature of Canada's mission in Iraq.

"Why did the government put them in harm's way after promising Canadians they wouldn't be at the front — that's the real question," Mulcair said.

Defence Minister Rob Nicholson insisted nothing had changed. "We have been very clear throughout… we are there to assist the Iraqis in their fight against this terrorist organization and we are there in support of our air fighters who are operating out of Kuwait."

Liberal Leader Justin Trudeau also challenged the defence minister on the parameters of the mission.

"The government said our ground forces would advise and assist, but not accompany Iraqi troops," Trudeau said. "Now we find out, they're routinely on the front lines. Why did the government mislead Canadians?"

Defence Minister Rob Nicholson maintained the mandate of the mission has not changed.

"I'm not sure how you can train troops without accompanying them... We've been very clear that we would be in the business of assisting and training these individuals."

The Liberals said that statement contradicts what Prime Minister Stephen Harper told the Commons last fall.

Asked about the rules of engagement, Harper said Canadian troops were in Iraq "to advise and to assist. It is not to accompany," Harper said on Sept. 30, 2014, before the first 30-day mission was set to end on Oct. 4.

The government extended Canada's involvement in the fight against Islamic jihadists in the Middle East to include air combat but no ground troops for a period of six months, in a motion tabled in the House of Commons on Oct. 3. The mission was approved in Parliament on Oct. 7.

House of Commons Speaker Andrew Scheer, following question period, turned down a request by the NDP for an emergency debate to address what the New Democrats said are "growing concerns" about the expansion of Canada’s military mission to Iraq.

Scheer said the request did not meet the requirements for an emergency debate.

A spokesman for Harper said Canadian troops are operating within the mandate provided to them by Parliament.

"Everything they are doing is consistent with an advise and assist role," Jason MacDonald told CBC News in an email on Monday.