A new Conservative attack ad takes aim at Liberal Leader Justin Trudeau’s position on the mission against the Islamic State, but it uses the terrorist group’s own horrifying propaganda images.

In the online ad, posted on the Conservative Party’s Facebook page, Trudeau is shown in a CBC interview saying he would end the CF-18 bombing campaign against the terrorist group, also known as ISIS or ISIL.

The ad uses Islamic State propaganda, including gruesome images of prisoners facing death by drowning and beheading -- and those images may actually violate the government’s own anti-terror law.

The new C-51 legislation gives a judge “the power to order the seizure of terrorist propaganda or, if the propaganda is in electronic form, to order the deletion of the propaganda from a computer system.”

“Here they are using the music and images of a terrorist organization. So not only does it undermine decency, but it undermines the credibility of the Conservatives on their own bill,” NDP MP Paul Dewar told CTV News.

Advertising executive Tony Chapman wondered how the uses of ISIS imagery would help the Conservatives score political points.

“Not only are they providing free advertising for ISIS, they’re completely offside and driving Canadian politics to a new low,” said Tony Chapman.

Meanwhile, Prime Minister Stephen Harper continued the political attack Thursday during remarks to reporters in Quebec City.

Harper suggested Trudeau would cut relations with Canada’s coalition allies in the fight against Islamic State in Syria and Iraq. He also accused Trudeau of wanting to “become best friends” with Iran, “one of the state sponsors of terrorism in the world.”

He then slammed Trudeau and NDP Leader Tom Mulcair for “irresponsible electoral politics” in their positions on the anti-ISIS mission.

The federal NDP made huge strides in Quebec in the last federal election, picking up 58 of the province’s 75 seats to help them reach a total of 95 seats in the House of Commons.

Mulcair has already stated that he would pull Canadian troops out of Iraq if he becomes prime minister. He said last March the NDP would be open to Canada participating in a UN or NATO mission, but not “an American-led mission.”

Harper’s comments about Trudeau come days after the Liberal leader said he would halt Canada’s bombing missions against ISIS in favour of sending military personnel over to train local troops on the ground.

On Thursday, Trudeau reiterated his position.

“We just don’t necessarily do it in the way Mr. Harper doing by dropping bombs; there’s much we can do around training and humanitarian support,” he said.

Trudeau has also said he would explore re-opening relations with Iran. In 2012, Canada suspended diplomatic relations with Iran and closed its embassies in that country.

With a report from CTV’s Richard Madan