Sources tell CTV News that a temporary halt to the processing of some Syrian refugees was ordered earlier this year to make sure the types favoured by the Prime Minister’s Office were being prioritized.

Department of Citizenship and Immigration insiders told CTV’s Ottawa Bureau Chief Robert Fife that PMO staff went through the files to ensure that persecuted religious minorities with established communities already in Canada -- ones that Conservative Leader Stephen Harper could court for votes -- were being accepted. Insiders say PMO actively discouraged the department from accepting applications from Shia and Sunni Muslims.

Private applications, which are often from church groups, were allowed to continue while the rest were on hold.

But the Conservatives said the halt was needed so that an audit could be undertaken to protect public safety.

“The audit we asked for earlier this year was to ensure these policy objectives are being met,” Harper told an audience in Vancouver.

“Political staff are never involved in approving refugee applications,” Harper added. “Such decisions are made by officials in the Department of Citizenship and Immigration”

Conservative Candidate and Transport Minister Lisa Raitt defended the halt on CTV Power Play, saying an audit was needed “to make sure that what we were trying to achieve from a policy point of view was actually being carried out.”

“In the case of these refugees, you want to make sure two things,” Raitt said.

“Number one, that you are getting the most vulnerable refugees, the ones that are ethnically and religiously in the minority in that part of the world. And second, you have to make sure that officials are applying the filter with respect to security.”

“The good news is,” Raitt added, “both were found to be true, so once that audit was completed, they started taking applications again.”

Raitt said the audit was not conducted by PMO staff, but she could not say who did it, adding that it’s not her portfolio.

Raitt also said “nothing had been turned over or changed in the applications.”

NDP Leader Tom Mulcair told a crowd in Toronto that “everybody knows that the government of Canada has the wherewithal to do the types of security checks that everyone knows that we need.”

Mulcair later told CTV Power Play that Harper should “apologize” for having been “two-faced,” after a photo of three-year-old Alan Kurdi’s lifeless body on a Turkish beach thrust the refugee crisis into the spotlight.

“(Harper) stood there and emoted about that young boy (Kurdi) that we all felt so bad about,” Mulcair said, “when he knew he was taking steps to stop families exactly like that one from coming to Canada.”

Liberal Leader Justin Trudeau told supporters in Vaughan, Ont., that the halt is an example of how Conservative Leader Stephen Harper's actions are not aligned with those of Canadians.

"Canadians, regardless of who they vote for and which party they line up with, need to believe that the Prime Minister's Office is there to serve them with integrity and with responsibility," Trudeau said.

Loly Rico, co-director of the FJC Refugee Centre in Toronto, said she believes the temporary halt on applications was an attempt to not bring in as many Muslims to Canada.

Immigration Lawyer Chantal Desloges explained on CTV Power Play that the UN does a “generic screening” of refugee applicants looking for “something obvious” that would exclude them, such as “people who have committed war crimes” and that the Canadian visa office then does its own check for security risks and criminals.

Desloges noted that “there were some intelligence reports that came out, as well as some media reports, that groups like ISIS … had been planting terrorists within those refugee groups, trying to get them into the west.

“So I think there’s probably a legitimate concern at a national level in which the PMO might have been interested.”

Desloges said she wants to know, however, whether it was a “purely procedural audit” or if the PMO staff was “looking at individual files,” as that would be “a matter of really serious concern.”

After facing criticism over the speed at which Syrian refugees have been proceeding, the Conservatives have pledged to fast-track the number of refugees into Canada, with 10,000 resettled by September 2016.

The NDP has vowed, if elected, to bring in 10,000 by the end of 2015, and 46,000 over four years.

The Liberals have said that Canada should take in 25,000 Syrian refugees before next year.