Conservative Leader Stephen Harper faced more tough questions Wednesday about Canada’s response to the refugee crisis, but he continued to brush off suggestions that Ottawa is not doing enough to help.

Speaking to reporters in Welland, Ont., Harper maintained that Canada is the largest re-settler of refugees per capita in the world “by far,” the biggest per capita donor of humanitarian aid to the affected region and is “committed to taking on the terrorists who created this problem in the first place.”

Harper has been repeating that message for days. While the Conservatives cite a report saying that Canada admitted a total of 12,300 refugees in 2014, the Canadian Council of Refugees says that per capita, Canada is in 6th place. That’s behind countries like Australia, Sweden and Norway.

The UN refugee agency also ranks Canada in 8th place when it comes to humanitarian aid.

Harper said Wednesday he’s committed to bringing more refugees to Canada while at the same time “protecting Canadians from the security risk.”

When asked why dangerous people among the throngs of refugees and migrants can’t be weeded out, Harper responded that, “there are 50 million people; we cannot bring them all.”

“We’re going to make sure we identify the most vulnerable people from the most vulnerable groups. We’re also going to make sure, when we’re talking about a significant number of people who come from a terrorist war zone … that all screening is done to make sure we protect the security of Canada and Canadians.”

Harper made the comments after Liberal Leader Justin Trudeau accused him of “seeking excuses to not do more.”

At a campaign rally in Toronto, Trudeau said: “Harper has recently brought up concerns around security, and of course security is important and we have processes whereby we’ve dealt with that.”

The war of words comes just as the head of the European Union urged EU nations to agree to share 160,000 refugees, and one day after Australia said it would resettle 12,000 Syrian refugees on top of the roughly 14,000 it normally resettles each year.

A growing number of prominent Canadians, including Former Chief of Defence Staff Rick Hillier, have called on Canada to take on more refugees.

“I wonder why we, as the great country that we are, could not stand tall during these dark days for the hundreds of thousands of displaced souls who are fleeing, quite literally, for their very lives,” Hillier wrote on Sunday in a widely-shared Facebook post.

“Each of our federal leaders has said we must do more, so let's do it. Have Harper, Mulcair and Trudeau agree that we'll focus on this now. Agree to bring 50,000 of those frightened men, women and children to Canada. Say we'll do it by end-December,” Hillier wrote.

On Wednesday, Hillier told CTV’s Power Play he’s frustrated because “we fail to stand tall in the world as a G7 nation, as a founder of United Nations.”

He said Canada can and must do more to help refugees.

“I think we need to step up, I think we need to alleviate some of that misery and I think we need to do it in a big way,” he said.

Hillier added Canada is capable of bringing in 50,000 refugees and “responsibly” screening them for any security risks.

Former Liberal Foreign Affairs Minister Lloyd Axworthy told Power Play that “people are very frustrated with the lack of government action on this issue.”

He also said there needs to be more international co-operation and collaborative agreements to keep refugees off dangerous boats that often capsize en route to European shores.

Foreign Affairs Minister Rob Nicholson, one of the leads on the refugee file, was with Harper on the campaign trail Wednesday, but Conservative security staff prevented reporters from asking him any questions.

Green Party Leader Elizabeth May brought up the migrant crisis Wednesday at her campaign platform launch in Vancouver.

“The system that’s now in place for refugees in Canada is not a welcome mat -- it’s a locked door, and you need to find the secret code to get through,” May said.

“It’s not that it’s difficult to get through because of red tape, it’s difficult to get through (by) design,” she asserted.

May pointed out she had opposed a Conservative-introduced amendment to the Immigration and Refugee Protection Act that allows groups of refugees arriving on boats to be deemed “irregular” and their occupants detained for up to one year.

The NDP recently announced it would settle 10,000 government-sponsored refugees by year’s end, followed by 9,000 more annually for the four years after that. The New Democrats would also fast-track private sponsorship and provide health care to refugees.

The Liberals have committed to settling 25,000 government-sponsored refugees in Canada by Jan. 1, 2016.

The Conservatives say they have resettled 22,000 refugees from Iraq and 2,300 from Syria since the crisis began, and that they would bring in 10,000 more refugees from Syria and Iraq over four years.

In an interview with CTV’s Mercedes Stephenson Wednesday evening, Defence Minister Jason Kenney said the world is not just dealing with a Syrian refugee crisis, but a “Middle Eastern refugee crisis.”

He said it all started in 2006, when the al-Qaeda terror group in Iraq began unleashing violence against religious and ethnic minorities in the country, who then fled to Syria. Many refugees from Syria originally came from Iraq, he said, and the humanitarian crisis affects both countries.

Kenney said Canada has lived up to its promise to resettle 23,000 Iraqis, many of them coming from Syria. He also repeated Harper’s message that the “first thing we need to do is stop the genocidal violence” that has devastated the region.

With a report from CTV’s Ottawa Bureau Chief Robert Fife, files from The Canadian Press and CTVNews.ca’s Josh Dehaas