OTTAWA -- The man who investigates electoral fraud in Canada says some investigations will simply "abort" if he isn't given the power to compel testimony from witnesses.

Yves Cote, the commissioner of elections, provided another direct critique of the Conservative government's electoral reform bill in testimony to a parliamentary committee Tuesday evening.

The bill makes sweeping changes to how elections are conducted and funded by provides Elections Canada with no new powers to investigate problems.

The chief elections investigator refused to discuss any specific cases, including the ongoing investigation into fraudulent robocalls in the 2011 election, but said unco-operative witnesses have been a real issue in his 20 months on the job.

"There have indeed been cases -- a number of them -- where in the performance of our investigative powers we have come across people who had information relevant to our investigations who simply refused to talk to us," said Cote.

"That has happened more than once -- including in matters of some significance," he added, after a pregnant pause.

Pressed for details, Cote would only say "some investigations will abort because of our inability to get at the facts."

Cote also told MPs on the committee the government is making a mistake by separating his office from Elections Canada and housing it with the Director of Public Prosecutions, which answers to cabinet.

The separation, he said, will slow down investigations, create communication problems, and goes against principles established by regulatory bodies such as the Canada Revenue Agency, the Competition Bureau and the Canada Border Services Agency.

Cote says he was never consulted on the proposed move.

"So more costly, less prosecutions is a very likely scenario -- and the public loss of confidence in terms of the independence of your office," summarized Liberal MP Kevin Lamoureux.

Conservative MP Erin O'Toole asked Cote whether his office would benefit from "a public confidence standpoint" by being independently housed from Elections Canada.

"I don't," Cote flatly responded, insisting he's already independent and if Parliament wants to reinforce that fact it can simply add a clear statement to the existing Elections Act.

Bill C-23, dubbed the Fair Elections Act by the Harper government, has been roundly criticized by current and former chief electoral officers, elections experts in Canada and abroad and by newspaper editorials across the country.

Cote's testimony was eagerly anticipated because the Conservatives insist they are giving him new independence by moving Elections Canada's enforcement arm into a separate bureaucracy overseen by the attorney general, a cabinet minister.

His assessment was bolstered by William Corbett, who served as commissioner of elections from 2006 to 2012.

Corbett told the committee that removing the commissioner from Elections Canada would do nothing to enhance his independence, but would hurt the oversight of federal election campaigns.

He noted that no one, up until now, has commented on the crucial role the elections investigators under the commissioner play during the 35-day campaigns, chasing down issues on behalf of Elections Canada.

That role would end under the Fair Elections Act, and there's no one else to pick it up, said Corbett.

After a 40-year career in policing and investigations, Corbett also said putting investigators in the Public Prosecutors Office is not a good fit.

"Prosecutors generally want to take an independent view of an investigation after it's completed. In fact, the less they have to do with the investigators beforehand, the better."

He said his experience was that "significant voter fraud," which Bill C-23 hopes to address, is not taking place -- and indeed the 60 per cent of Canadian electors who routinely cast a ballot are typically very serious and conscientious.

But he lamented the "adversarial context" that's been injected into the elections process in recent years and the fact party workers have begun refusing to co-operate with Elections Canada.

Corbett made a number of references to the ongoing robocalls investigation that began under his watch before he retired in 2012.

"I don't want to dwell on roboballs too much, but we had no idea what can be done on the Internet by way of triggering 100,000 calls for a very small price. I don't know what's coming next," Corbett concluded with a rueful laugh.