Conservative MP Maxime Bernier, who raised eyebrows this summer by claiming he received 1,000 complaints a day over the mandatory long-form census in 2006, says the government's decision to make it voluntary is about "principle," not the number of complaints.

Conservative MP Maxime Bernier says he can't recall the details of each complaint he received about the 2006 census when he was industry minister. (Tom Hanson/Canadian Press)His comments come after internal documents obtained by CBC News show an Industry Canada employee questioned Bernier's claim in July that he was blitzed by complaints four years ago when he oversaw the census as industry minister.

Bernier, currently a backbencher, told CBC News on Tuesday that he cannot prove his office received the number of complaints about the census because the emails were deleted. He added he doesn't recall the details of each complaint.

"Yeah, it was about a thousand a day, but I'm not sure from that thousand how many were on the census itself," he said outside the House of Commons. "So we had a discussion with my staff and we cannot prove it because all these emails have been deleted from that time, four years ago."

Bernier, who resigned from Prime Minister Stephen Harper's cabinet in 2008 after he admitted to having left NATO briefing documents at his ex-girlfriend's home, said his estimate was made in "good faith" based on what he was hearing from his staff and constituents as an MP.

But he also insisted it shouldn't matter because the decision to make the survey voluntary is a "principle position."

"It’s all about freedom, and not about complaints," he said.

Industry Minister Tony Clement said he would not speak for the former minister, but added the public policy is justified if there is just one complaint. The minister also said Canadians who had a complaint about the census wouldn't take their concern to Statistics Canada.

But the documents, obtained by CBC News through an access-to-information request, suggest officials inside the ministry responsible for the census were themselves caught flat-footed by Bernier's contention that the government had been inundated with complaints over the 2006 survey.

22 complaints about census 'intrusiveness': StatsCan

In a July 18 email, ministry employee Paul Halucha asked a high-ranking official at Statistics Canada whether the agency had any numbers to back up Bernier's statement. Industry Canada's "internal survey of correspondence did not show anything close to a thousand a day," he wrote to Statistics Canada's Connie Graziadei, adding in brackets "we got a standard 25-30 a year."

According to the documents, Graziadei replied with a breakdown of the 882 complaints Statistics Canada received for the 2006 short- and long-form census, which included 332 complaints about a contract the agency awarded to Lockheed-Martin for census data collection.

In her email, she said Statistics Canada received 22 complaints about the "intrusiveness of the questions." There were also 116 about the "subject matter" of the questions.

But nowhere in the documents does Statistics Canada list anyone complaining about the long-form census being mandatory, despite numerous Conservative MPs saying they've heard an earful from constituents about having to fill out the 40-page form.

For months, opposition parties have been pushing the government to reverse its decision and reinstate the mandatory long-form census, citing an outcry from statisticians, various social, language and religious groups, as well as some provinces and municipalities that the quality of data from a voluntary survey will be lowered.

The Conservatives have said the move to a voluntary long-form survey is a "balanced" approach that weighs the need for data with the concerns of Canadians who feel they shouldn't be threatened with fines or jail time to divulge personal information to representatives of the state.