The RCMP has released an additional 18 seconds of the video made by shooter Michael Zehaf-Bibeau that were withheld when the rest of his recorded explanation for his plan to kill soldiers in Ottawa was made public in March.

The extra footage released on Friday sheds little additional light on the motivation for the attack.

Mr. Zehaf-Bibeau used his cellphone to record the one-minute statement in his car on Oct. 22, shortly before killing Corporal Nathan Cirillo at the War Memorial and then storming Parliament's Centre Block with a rifle and a knife. The first 13 seconds of previously unseen video, which open the recording, contain a common Muslim prayer recited in Arabic in which the shooter asks Allah to "open my chest, ease my task for me and remove the impediment from my speech."

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The five additional seconds of footage at the end of the video show Mr. Zehaf-Bibeau asking for peace for the mujahideen and then saying: "May Allah curse you."

The RCMP said in a statement on Friday afternoon that the force believed the content that was initially held back could help determine the origin and nature of Mr. Zehaf-Bibeau's radicalization to violence.

"The RCMP also needed time to fully analyze the language used, including the dialect of Arabic being spoken, consult subject matter experts and follow up on a number of investigative leads," the force said.

In the portion of the video that was made available to the public in March, Mr. Zehaf-Bibeau says, in English, that the actions he was about to take were in retaliation for Canada's role in Afghanistan and Prime Minister Stephen Harper's intention to send troops to Iraq to fight against the Islamic State.

"Just aiming to hit some soldiers just to show that you're not even safe in your own land," he says into his cellphone. "Stop going to other countries and stop killing the righteous of us who are trying to bring back religious law in our countries."

The federal government has invoked the shooting to justify the need for the new anti-terrorism powers in Bill C-51.

After the release of the additional seconds of video on Friday, Public Safety Minister Steven Blaney commended the work of the RCMP and other police who helped end Mr. Zehaf-Bibeau's rampage.

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"Last fall's attacks demonstrated all too clearly that Canada is not immune to the threat of jihadi terrorism," Mr. Blaney said in a statement. "This video is a stark reminder of the need to remain vigilant at home and abroad."

Bill C-51 would beef up the powers of the Canadian Security Intelligence Service, criminalize the promotion of terrorism and provide the RCMP with new powers of preventive arrest. The bill would also ease the transfer of information between some federal agencies and criminalize the promotion of a terrorist attack.

But critics charge it goes too far and could ensnare environmentalists and native people.

Speaking to reporters after the daily Question Period in the Commons, NDP defence critic Jack Harris said of the release of the additional footage: "I hope the Prime Minister and the government doesn't try to use this once again to frighten Canadians."

Bill C-51 passed the House of Commons with the support of Conservative and Liberal MPs earlier this month, with the NDP opposed. It is expected to become law before the House rises for its summer break in June.

With a report from Daniel Leblanc