VANCOUVER - Prime Minister Stephen Harper stood by his government's decision Monday to stop making completion of the long census form mandatory and said his party will not use fines or jail terms just to get the public's co-operation.

Harper commented about the census controversy for the first time during a press conference in Vancouver.

The federal government has said next year's long-form questionnaire will be voluntary and go to 30 per cent of households. The form could be cancelled completely in the future.

Critics and bureaucrats in department after department have warned the government the data is needed.

Making the long form voluntary, they said, would lead to lower quality data at a far higher cost. Vulnerable groups, such as aboriginals and low-income people, would be lost in the new survey, while middle-class white people would be over-represented.

But Harper, who addressed reporters in front of a beluga whale exhibit at the Vancouver aquarium, stood by the move.

"This has detailed personal information that is being sought by the government," he said. "I know some Canadians will have some reluctance to provide that and I know some people think the appropriate way to deal with that is through prosecuting those individuals with fines and jail terms.

"This government will not do that. In this day and age, that is not an appropriate way to get the public's co-operation."

Harper's government has been under pressure to reverse its decision on the long-form census, which sparked the resignation of the head of Statistics Canada.

News that the government had killed the mandatory nature of the form broke at the end of June.

It set off a blizzard of criticism from groups as diverse as the Canadian Jewish Congress and the Federation of Francophone and Acadian Communities.

The Federation of Francophone and Acadian Communities tabled papers in Federal Court on July 26 asking the court to void the new policy.

Tory defenders have called the mandatory form a violation of privacy.

Critics have said eliminating the mandatory nature of the form will make it more difficult, among other things, to determine the need for some social programs and participation rates in them.

The plan was eventually announced quietly on the last Saturday in June, when public attention was consumed by the G20 riots, the international summits in Toronto and Huntsville, and the Queen's visit to Canada.

It was contained in a published order-in-council, as cabinet decisions are called. Or rather, the long census simply didn't show up in the document.

Information about this fundamental change to a 40-year-old product did not appear in Statistics Canada's daily releases on their website. Instead, one had to click on a small link called "Census 2011" that was never publicly pointed out.

Few people outside the top ranks of government had an inkling it was even in the works. No one outside government had been consulted -- even groups with whom Statistics Canada was in regular contact about how to frame the next census.

And the announcement was left until the last minute, leaving just a few weeks between its publication and the date Statistics Canada needed to start work on implementing the new arrangement.

But if there were ever any hopes of the issue being lost in the haze of summer, they were quickly dashed.

Within a day of The Canadian Press reporting the announcement, municipal governments realized the information they rely on to make almost every key policy decision was about to be eroded.

Opposition Liberals have called on the Commons industry committee to reconvene over the Tory government's refusal to produce documents related to its decision.