The number of complaints about fraudulent or misleading telephone calls in last year's federal election has almost doubled, according to court documents filed by the Commissioner of Canada Elections.

By mid-August, Elections Canada had received 1,394 complaints "alleging specific occurrences" in 234 of Canada's 308 federal ridings, the lawyer for the elections watchdog says.

That's up from the more than 700 specific complaints that the commissioner's office publicly reported in March to clear the air after an online campaign attracted 30,000-plus expressions of concern by Canadians.

But the elections commissioner, in his latest court offering, declined to respond to a number of other disclosure requests by advocacy group the Council of Canadians.

"Like all law enforcement agencies, the Office of the Commissioner treats complaints and the office's ongoing investigations in confidence and discloses neither the information collected nor the source of the information, except as necessary for law enforcement purposes," wrote John Laskin, representing the commissioner's office.

The letter goes on to "emphasize" that the total number of complaints and ridings "does not provide any indication of whether complaints are ... substantiated, or whether complainants reported their voting behaviour to have been affected."

Allegations of fraudulent and misleading phone calls designed to suppress the vote of targeted constituents during the May 2, 2011, election are currently being investigated by the commissioner's office.

Marc Mayrand said this spring that the investigation "touches on the fundamentals of our democracy, how we elect our representatives. I can't see anything more serious than that in our democratic institutions."

The investigation has centred on Guelph, Ont., where a number of residents say they received automated phone calls from someone claiming to be from Elections Canada and directing them to a wrong or non-existent polling station.

While the misleading phone calls appeared to target non-Conservative voters, the Conservative party insists it had no involvement in any such scheme and says it is assisting the investigation.

Court challenge seeks to overturn results

The Council of Canadians, a nationalist, left-leaning advocacy organization, is leading a parallel court battle to contest the election results in seven closely-fought ridings, arguing that misleading calls to voters may have skewed the outcome.

The group wanted specific information from Elections Canada on the location and nature of robocall complaints, and how many separate investigations are underway, in order to bolster its case.

New elections commissioner Yves Cote submitted a lengthy certificate to the Federal Court dated Aug. 17, declining to release much of the requested information.

Cote cited four main reasons for his non-disclosure:

Protecting the integrity of an ongoing investigation.

Maintaining public confidence in the fairness of the electoral process and enforcement of the elections rules.

Protecting the presumption of innocence.

Ensuring the commissioner remains impartial and non-partisan, and is perceived as such by the public.

"It's important to know (the number of complaints) has increased," Maude Barlow, the chairperson of the Council of Canadians, said in an interview. "That, I think, makes our case stronger and the concern of Canadians stronger."

But Barlow wasn't buying Elections Canada's reasons for not disclosing more, saying the information should be public.

"We we would like to know what ridings, we would like to know the actual nature of the complaints. We feel that people have a right to the kinds of details that simply are not there."

The council's case is to be heard in Federal Court in December.