The Canadian Food Inspection Agency is defending its handling of a nationwide beef recall as critics questioned why it took three weeks to shut down an Alberta meat processing plant at the centre of an E. coli scare.

Operations at XL Food’s massive plant in Brooks, Alta., will not resume until “corrective measures” are implemented and food safety testing standards are up to par, CFIA’s special advisor, Brian Evans, said at a news conference Friday.

“Our top priority is maintaining the safety of the food supply,” Evans said. “To date the company has not implemented agreed-upon corrective actions.”

He said all products currently at the plant are under CFIA “detention and control,” and will be released only after being tested for dangerous strains of E. coli, a bacterium that can lead to fatal illness.

Concern about the recall made its way into question period Friday on Parliament Hill, with NDP and Liberal MPs blasting Agriculture Minister Gerry Ritz for cuts they said the Conservatives had made to food inspection.

“Why did it take so long for officials to act and why isn’t the government putting the health and safety of Canadians first?” asked NDP MP Libby Davies, whose comments were echoed by fellow NDP MP Nycole Turmel.

Liberal MP Ralph Goodale garnered boos from the Conservative caucus when he charged that similar complacency about safety controls had led to the Walkerton tragedy, which resulted in several deaths after people drank contaminated water in Walkerton, Ont. in 2000.

Goodale asked why it took so long to accurately determine the scope of the latest E. coli threat.

“Is it because the government fired 90 biologists?”

Ritz responded by calling Goodale “another ill-informed opposition member.”

“If he would care to remember, the system that CFIA is using now, called CVS, was brought in 2005 under his government,” Ritz said.

He added that the government is providing CFIA with the resources it needs and said the system is working as it’s supposed to.

“The timeline backstops the fact our system does work,” Ritz said. “There is no endemic situation out there from E. coli.”

Other critics compared the situation in Alberta to the listeriosis outbreak at a Maple Leaf Foods plant in Ontario four years ago.

“I mean, this is the guy who made jokes during the listeriosis crisis,” NDP MP Megan Leslie said, referring to reports that Ritz made light of the issue at the time by saying: "This is like a death by a thousand cuts. Or should I say cold cuts,” during a conference call.

“I don’t think they’re taking it seriously,” Leslie said.

The CFIA defended the Canadian inspection process Friday, saying XL Foods took steps early in the recall to ensure the safety of its food and committed to additional steps to deal with the problem.

When tests first detected a possible E. coli problem at the plant, there was no indication that tainted meat had reached consumers, Evans said.

"The primary issue at that time was to identify if, in fact, there was any product in the marketplace that needed to be recalled,” he said. "We did confirm that neither the product that we had found through our testing program or the product that the U.S. had identified ... had gone into the marketplace. Issuing a recall for a product that isn't in the public domain isn't something that we're able to do."

An "intensive, in-depth review" was launched when the CFIA received more information on Sept. 10., Evans said.

"We were 24 hours, pedal-to-the-metal, in the plant through the (Sept. 15-16) weekend trying to satisfy ourselves that consumers were not being put at risk," he added.

However, as the probe intensified, the CFIA realized this week that “deficiencies” at the plant “have not been completely corrected,” Evans said.

The suspension of XL Food plant’s license came hours after the U.S. Department of Agriculture extended its public health alert about beef from the company to stores in 30 states.

Canada had already revoked the plant's permit to export beef to the U.S., at the request of the USDA.

That came almost two weeks after the CFIA detected E. coli in products produced at an Alberta facility supplied by XL Foods. That same day, USDA also detected E. coli in beef trimmings from XL Foods.

Since then, the CFIA has issued at least eight recall alerts involving ground beef products from the plant. The recall has since been expanded to more than 250 products sold in Canada and the CFIA said the list will likely grow.

The CFIA said the detection of E. coli in slaughter facilities is “not uncommon.” It says food processing plants are supposed to monitor levels of the bacteria so they can spot higher-than-normal rates and take steps to control the bacteria.

“This trend analysis was not always conducted consistently at the facility,” the CFIA said in a news release.

There have been no confirmed cases of people getting sick from eating ground beef from the plant.

However, at least four people in Alberta have fallen ill with E. coli poisoning in recent weeks. The CFIA says they became ill after eating E. coli-tainted strip loin steaks sold at an Edmonton Costco store under the Kirkland brand.

Though the steaks came from the XL Foods plant, health officials aren't sure if the E. coli got on the steaks at the plant or if it came from a metal meat tenderizing machine used at the Costco store.

The store has said it would no longer use the tenderizing machine.

With a report from CTV’s Chief Political Correspondent Craig Oliver and files from The Canadian Press