Advocates for whistleblowers said the appointment of Mario Dion as the new public sector integrity commissioner is an "unwise" one Wednesday and asked MPs to reject the nomination.

"There are many reasons to fear that Mr. Dion will prove to be an ineffective integrity commissioner, perhaps no better than disgraced former commissioner Christiane Ouimet," David Hutton, executive director of a group called FAIR, said at a news conference on Parliament Hill.

He said MPs are "woefully unaware" of Dion's performance as interim commissioner and if he and other groups had been given a chance to testify Tuesday at a parliamentary committee, they would have drawn attention to it.

Dion appeared at the government operations committee to testify about his appointment as the new commissioner, announced last week, and Hutton said it is "absurd" that no other witnesses were called.

"This is not democratic, it's not ethical, it's not honourable, it's not sensible," said Hutton.

The office was set up in 2007 to hear confidential complaints from public servants or members of the public about potential wrongdoing in the federal public service.

Dion has been serving as the agency's interim commissioner since Ouimet left in late 2010 under a cloud of controversy and with a hefty departure package worth more than $500,000.

Ouimet abruptly quit in the midst of a review of her office by former auditor general Sheila Fraser. Fraser's report said Ouimet acted inappropriately with staff in her office, retaliated against people she thought filed complaints about her, and didn't do her job. She described Ouimet's conduct as inappropriate and unacceptable, particularly given that her job was to protect public servants from reprisal.

Hutton said he and other groups that try to help whistleblowers have been shut out of committee meetings since the office was created.

"It's because of this shutting out of civil society that for years MPs had no clue of what Ouimet was doing. If we had been called to testify following any of her annual reports in 2008 or 2009 or 2010 then the problems could have been exposed and this entire fiasco could have been nipped in the bud," said Hutton. "But that didn't happen."

Ouimet investigated only a handful of the 228 complaints she received over her three years in office and didn't once find a case of wrongdoing.

In one case, she decided not to investigate a complaint by veteran Sean Bruyea that his personal medical information was used against him by Veterans Affairs officials. Jean-Pierre Blackburn, the minister for the department, later apologized to Bruyea and the government settled a lawsuit with him over the privacy breach.

Bruyea was at the press conference Wednesday and said Ouimet shut down his file without even interviewing him. When Dion took over as interim commissioner an independent review of all complaints to the office was ordered, but Bruyea says the review of his case was not independent and that Dion had a hand in it.

Dion also chose to close his file and Bruyea said he's done exactly what Ouimet did: "protected those who break the law."

"Instead of using every power of his office to pursue bureaucrats who violate our trust, Mr. Dion appears to use every power of his office to defend such violators while curiously condemning the violations. In doing so, Mr.Dion shows he is far too immersed in the artificial and highly disconnected world of Canada's senior federal civil service, a culture of entitlement and excessive privilege," said Bruyea.

Bruyea said based on his experience with Dion's office over the last year he wouldn't advise fellow whistleblowers to count on it for protection and he instead recommend they get legal advice and rely on groups like FAIR for help.

The whistleblower groups say Dion is in a conflict of interest in taking over the office permanently and that his long career in the public service (he was assistant deputy minister of justice and has worked for the privy council office, National Parole Board and other departments) means he risks investigating people he knows and has worked with over the years.

Dion told the committee on Tuesday that he believes his experience in the public service will be an asset for him in his new job.

With files from CBC News