The union representing Canada's food scientists and inspectors issued its own call on Friday for Stephen Harper to fire federal Agriculture Minister Gerry Ritz, saying he has "repeatedly disappointed" those who work for him during the listeriosis crisis.

The head of the Professional Institute of the Public Service of Canada, which represents 1,800 food inspection and health protection workers, described Ritz's jokes about the crisis linked to 17 deaths across the country as "the last straw."

"Crisis requires real leadership, and Mr. Ritz is clearly not fit to lead," the union's president, Michèle Demers, said in a release Friday.

It was revealed earlier this week that Ritz had cracked jokes about the outbreak while he was on a conference call with scientists and political staffers on Aug. 30.

During the call, Ritz said the political fallout from the outbreak was "like a death by a thousand cuts. Or should I say cold cuts."

When he was told about a new listeriosis-linked death in Prince Edward Island, Ritz said, "Please tell me it's Wayne Easter," referring to the Liberal agriculture critic.

Canada facing 'food crisis': Layton

The controversy continued to dominate the Oct. 14 federal election campaign for a second day on Friday as opposition leaders stepped up their attacks on the Conservatives.

Harper, speaking Friday at a campaign stop in Quebec, again dismissed calls to fire Ritz, saying the minister "clearly did not intend to make any such comments publicly and has thoroughly apologized."

He also said his government has committed to a full inquiry into the outbreak to ensure similar events do not happen again.

But federal NDP Leader Jack Layton countered that Canadians are facing a "food crisis" while the Conservatives have failed to act.

"Since the crisis arose this summer, we have been getting new information almost every day with respect to the failure of the Canadian food inspection system," Layton told reporters in Ottawa on Friday.

Layton demanded Harper "show real leadership" and fire Ritz, while also committing to place a federal food inspector on the floor in every one of Canada's some 800 meat-processing plants and also reverse spending reductions on staffing.  

"The minister has been callously indifferent to the deaths and suffering of dozens of Canadians," the NDP leader said. "No one has any confidence in Mr. Ritz and he's got to be fired."

Layton also said the federal government must ensure that imported ready-to-eat meat products face the same stringent requirements as Canadian products.

Liberal Leader Stéphane Dion, appearing Friday alongside Easter at a farm policy announcement outside Winnipeg, accused Harper of trying to shift the blame to civil servants and then intimidate them into silence.

"He will not intimidate Liberals; he will not intimidate me," Dion said.

"Stephen Harper refuses to fire Gerry Ritz. Well, let's elect a Liberal government and we'll do it for him."