The government's decision to fire the head of Canada's nuclear safety watchdog hours before she was to speak about a nuclear shutdown in November will prevent public servants from speaking out about other important safety issues, says the head of the union representing federal public servants.

"This type of thing is going to stop them from even thinking about that, because they're going to say, 'Wait a minute, if I speak out my head's chopped off,'" said John Gordon, national president of the Public Service Alliance of Canada, on Thursday.

That could affect the safety of food and other issues beyond nuclear safety, he added while speaking on CBC Radio's Ottawa Morning about Tuesday night's dismissal of Linda Keen, president of the Canadian Nuclear Safety Commission.

Because she was no longer president of the commission, she did not appear before the committee Wednesday.

"The fact is that it [the firing] thwarted her ability to appear before the committee," Gordon said in an earlier interview, on Wednesday. "That's a pretty powerful message you're sending and not one that people are going to feel very comfortable about."

Keen, who is not a member of the union, was fired just before midnight on Tuesday, hours before she and Natural Resources Minister Gary Lunn were set to appear before a House committee in Ottawa on Wednesday.

Keen was to discuss the shutdown of a nuclear reactor in Chalk River, Ont., for safety reasons in November. The reactor produced two-thirds of medical isotopes used around the world to diagnose cancers and cardiovascular diseases, and its closure was blamed for a worldwide shortage of the isotopes.

Parliament overruled the nuclear safety commission and ordered the reactor restarted in December.

Lunn said Wednesday Keen was fired due to her "lack of leadership" regarding the situation.

But Canadians have not yet heard Keen's perspective, Gordon said.

"It would have been really good if the public could hear what she had to say about the issue and why the decisions that were made were made," he said. "And there's got to be background that we don't know yet."

University of Ottawa law professor Errol Mendes said it's a case public servants should be talking about.

"If essentially the message being sent is: 'Do what I say, move the way I want you to move and if you don't, watch out,' then potentially, the public service could be compromised," he said.

That could jeopardize the safety of medical devices, the food chain or anything else public servants oversee, he added.

Mendes said Keen's termination will likely result in a wrongful dismissal suit.

The commission ordered the Chalk River reactor to close on Nov. 18 over safety concerns about the emergency power system not being connected to cooling pumps, as required to prevent a meltdown during disasters such as earthquakes.

In December, Parliament ordered the facility to reopen amid a public outcry about medical tests being cancelled because of the isotope shortage.

Keen, who became head of the commission in 2001 and had been serving her second five-year term as president, remains a member of the commission.