Former foreign affairs minister Lloyd Axworthy says Canada needs to toughen its response to the Islamic State group, saying the terrorists “have to be whacked and whacked good.”

Several dozen Canadian special operations troops will embark on a 30-day mission to advise Iraqi forces battling the Islamic State.

“We’ve got some good soldiers over there, the best troops we have, but that’s not going to deal with the issue,” Axworthy told CTV’s Power Play on Monday.

“If you really want to stop them, you’re going to have to give a full-court press.”

The Harper government will review the mission once the 30 days are up to determine whether the mission should be extended.

Royal Canadian Air Force planes are also helping transport both military and humanitarian supplies to Kurdish forces in northern Iraq.

But Axworthy said Canada needs to do more.

“This is an act of war crime, it’s obnoxious and obscene, and these guys have to be whacked and whacked good,” he said.

NDP Leader Tom Mulcair opened the first question period of the new session of Parliament Monday by asking Harper about the mission. Mulcair then accused Harper of flouting a promise he made in the 2007 Throne Speech that future military deployments must be supported by a majority of Parliamentarians.

"That’s a direct quote from the prime minister. He puts his honour on the table," Mulcair said. "Now he's sending Canadian troops to join the war in Iraq without a vote in the House, without even a debate in this House. Why is the prime minister breaking his own solemn promise to Canadians?"

A majority government that "has the confidence of the House of Commons" has the right to advise the governor-general on military operations, Harper replied.

"That said, wherever there has been a deployment of a combat nature, the government has put this to Parliament for a further confidence vote," he went on. "That is not the case with the present mission to Iraq."

Both the Liberals and the NDP have called for a debate in the House on the deployment of troops to Iraq.

The back-and-forth in question period followed comments the prime minister made earlier Monday in a campaign-style speech in which he countered arguments that there are "root causes" for terrorism that must be addressed.

"Canadians are rightly sickened by (Islamic State’s) savage slaughter of anyone who doesn't share their twisted view of the world. We know their ideology is not the result of 'social exclusion' or other so-called 'root causes,"' Harper said, seeming to reference an interview in which Liberal Leader Justin Trudeau referred to root causes of terrorism.

"It is evil, vile, and must be unambiguously opposed."

Before Harper’s speech, Foreign Affairs Minister John Baird held a teleconference with reporters to discuss developments at a conference in Paris devoted to the international response to the threat posed by Islamic State.

French President Francois Hollande and Iraqi President Fouad Massoum co-hosted the meeting.

Baird and other foreign ministers have been critical of former Iraqi Prime Minister Nouri al Maliki for alienating Iraq's Sunni minority population, which some observers have identified as one of the root causes of the growth of Islamic State.

Baird told reporters Monday that the new Iraqi Prime Minister, Haider al-Abadi, who took office just last week, appears ready to form a more inclusive government.

"I was pleased to hear the comments by the president and the new minister of foreign affairs. I was also struck by the spirit in the room, particularly from the Sunni Arab neighbours of Iraq who are hugely encouraged by what they're seeing coming out of Baghdad,” Baird said.

Baird also denounced the recent killing of British aid worker David Haines who, like American journalists James Foley and Steven Sotloff, were likely beheaded by western fighters who travelled to the Middle East to fight with Islamic State.

"I think that there are people fighting from some 50 countries, likely from virtually every country from around the table this morning. Obviously we all want to do more," Baird said.

"For all of us, including my British counterpart, the fact that a development worker from the United Kingdom was most probably beheaded by another citizen of the United Kingdom was probably the most horrific thing we've learned in this battle."

Baird also called on the international community to join together in a united response to the Islamic State threat.

"We must not surrender this moment."

With files from The Canadian Press