OTTAWA - The heads of three federal agencies pivotal to last summer's listeriosis crisis want a damning report by Ontario's top public health official "clarified and corrected."

The most senior officials at the Canadian Food Inspection Agency, the Public Health Agency of Canada and Health Canada demanded the revisions in a recent letter to Dr. David Williams, Ontario's acting chief medical officer of health.

"We note that the document contains a number of statements which should be clarified and corrected for the public record," says the letter, dated April 20.

The letter is co-signed by CFIA president Carole Swan, chief public health officer David Butler-Jones and Health Canada deputy minister Morris Rosenberg.

They were not immediately available Thursday to comment. A call to Williams' office was not immediately returned.

Williams' report, released last Friday, wrapped the knuckles of federal and provincial health authorities for failing to work together during the outbreak.

Twenty-one people died and hundreds more fell ill after eating contaminated deli meats from a Maple Leaf Foods plant in Toronto.

The letter says Toronto public health officials hampered the investigation by not including enough identifying information on food samples collected from Toronto hospitals and nursing homes that tested positive for listeria.

"We share your frustration with the length of time over which recalls took place," the letter says.

"The CFIA acted quickly to recall specific food products as soon as it had the information it needed to initiate a response."

Williams saved his most pointed criticism for the CFIA. He described the food watchdog's inspectors as territorial for not allowing Toronto public health officials into the Maple Leaf plant that produced the tainted meat.

The CFIA told a special panel on food safety earlier this week that inspectors were never actually barred from the Bartor Road plant, and said it might have all been a "misunderstanding."

Williams also noted that almost a month elapsed between the first listeriosis death last summer and a widespread recall of suspect Maple Leaf deli meats.

The letter suggests that criticism is unfair.

"The report implies that the CFIA was remiss in not triggering a mandatory food recall," the letter says.

"A mandatory recall was not required in this case, as Maple Leaf removed the product as soon as it was confirmed to be a health risk."

Williams' report likewise singles out the Public Health Agency for not playing a leadership role during the outbreak.

Williams released his report last Friday ahead of separate "lessons learned" reports by the CFIA, Health Canada and the Public Health Authority.