OTTAWA — One of the biggest opponents of the long-form census within the Harper government actually defended the mandatory survey as an "essential" tool for Canada when he was industry minister, according to a newly released letter.

"Most of the questions that appeared on the 2006 Census long-form have appeared on many censuses," Maxime Bernier wrote in a letter dated Aug. 21, 2006, as minister responsible for Statistics Canada.

"These questions continue to be essential for providing the information needed by governments, businesses, researchers and individual Canadians to shed light on issues of concern to all of us — employment, education, training, transportation, housing, immigration, income support, pensions for seniors, transfer payments, aboriginal issues and many more."

The letter was sent to Liberal MP Bryon Wilfert, in response to concerns raised about the "length and detail" of the questionnaire from some of his constituents.

At a news conference Thursday, Wilfert said he passed on the constituents' inquiries to Bernier in order to seek clarification for them. He gave them the minister's response and there were no subsequent inquiries from the constituents, he said.

The government announced in the summer it would scrap the mandatory long-form questionnaire and replace it with a voluntary survey to respond to concerns about the intrusiveness of the questions. The move has prompted dozens of organizations who rely on the data to pressure the government to reverse its decision and the opposition parties are trying to get the government to reinstate the long-form census.

"Determining the questions to be asked in the census is a delicate balancing act that takes into account the diversity of interests and views that exist among our population," Bernier wrote.

"All of the questions are designed to meet important information requirements that would be extremely difficult to satisfy efficiently from other sources. In fact, every question goes through a rigorous consultation, testing, review and approval process, including that by cabinet."

Tony Clement, the current industry minister who has had the job of defending the government's controversial decision, was a member of that cabinet, Wilfert pointed out, suggesting he must have then shared Bernier's view outlined in the letter.

Bernier responded Thursday that his view on the mandatory nature of the census has changed since he wrote the letter to Wilfert.

"I changed my mind since that time, I wrote that letter four years ago," Bernier said in an interview. "And after that I had time to study all that and I think it's more important to choose the freedom of choice, to choose if they want to answer the long-form census or not."

Bernier said it's not right for people to be forced to answer the questions under threat of a fine or jail time and that he fully backs the government's decision.

Canadians currently are still subject to a fine or jail time if they don't fill out the short-form census but the government has pledged to introduce legislation to remove the jail threat from all mandatory surveys. Clement has not indicated when that bill will be ready.

Bernier said people shouldn't be forced to fill out the short form census either and that he hopes the legislation also removes the threat of a fine.

"For me, I think it will be a good decision if we don't have that threat either," he said.