OTTAWA -- Liberals are demanding an apology from Prime Minister Stephen Harper after a Conservative pollster was censured for conducting a misinformation campaign against MP Irwin Cotler.

An investigation by the market research industry's watchdog concluded Wednesday that the actions of Campaign Research Inc., brought the industry into disrepute.

"The actions of Campaign Research have likely caused the Canadian public to lose confidence in marketing research and have tarnished the image of the marketing research profession," says a ruling by three-member panel of the Market Research and Intelligence Association.

The panel was struck after the association received seven complaints of professional misconduct against Campaign Research.

The complaints related to a voter identification poll the company conducted last autumn on behalf of the federal Conservative party in Cotler's Montreal riding.

The company's callers suggested to constituents -- falsely -- that Cotler either had or was about to quit as the Liberal MP for Mount Royal.

Cotler said the Conservatives must now take responsibility for the conduct of their pollster.

"I think they should be severing their ties with the firm that undertook these acts on their behalf," he said.

"And they themselves should not only apologize, but undertake that they will not engage in such false and misleading voter suppression again."

When Cotler first complained a year ago about the polling being done in his riding, government House leader Peter Van Loan defended it as a routine matter of identifying Conservative support in Mount Royal.

"The fact is this has been going on as long as politics in this country," Van Loan told the House of Commons. "It is a normal part of politics in this country and it's not a kind of speech that should begin to be chilled at this point."

He was unrepentant Wednesday, dodging Liberal questions about the MRIA's ruling by saying that Commons Speaker Andrew Scheer ruled on the matter last December and, hence, there is nothing more to say.

"It's a settled issue," Van Loan insisted.

Cotler had asked Scheer to find that the polling impaired his ability to carry out his duties as an MP. Scheer ruled that the tactic was "reprehensible" but that he was powerless to do anything about it.

However, now that the MRIA has censured Campaign Research, interim Liberal leader Bob Rae said the Tories can no longer pretend this was "politics as usual."

"The effort to dislodge Mr. Cotler was, to use a technical term, disgusting," Rae said, demanding that Harper take responsibility for the ploy. "It was beyond any standard we've ever known.

"This didn't happen by accident. It happened because the Conservative party asked this organization to conduct such a poll."

According to a script provided to the MRIA panel by Campaign Research, callers told respondents: "I am calling on behalf of the Conservative party of Canada and the reason I am calling is to ask if Stephen Harper can count on your support in the upcoming election."

If asked what election was upcoming, the caller was to add: "Some people are suggesting that the current MP may retire so we're calling on behalf of Prime Minister Stephen Harper and the Conservative party of Canada to ask you if you would consider supporting the Conservative party of Canada if there is a byelection."

The MRIA is a voluntary body with limited powers to police the market research industry. However, it can suspend or expel members who violate its code of conduct, depending on the number and seriousness of the violations.

The panel did not recommend going that far with Campaign Research, although it said the company violated three provisions of the code and that the violations were "more serious than a minor transgression."

It settled on censuring Campaign Research, which essentially amounts to a public rebuke.

"Campaign Research accepts the conclusions and decision of the MRIA," the company's general counsel, Aaron Wudrick, said in an email.

"We remain proud gold seal members of the association and endeavour to continue our affiliation with the MRIA by striving to uphold the highest ethical and professional standards."

The panel concluded that the company violated a core principle of the code of conduct, to act in a manner that "serves to promote and augment, not diminish" public confidence in market research.

It also violated its professional responsibility to refrain from acting in any way that could discredit the industry and to refrain from using its membership in the MRIA to justify its actions, the panel said.

The panel was particularly disturbed by a television interview with Campaign Research principal Nick Kouvalis in which he insisted his company had followed the rules and pointed to its gold seal status with the MRIA as proof.

"We observe that Mr. Kouvalis ... used Campaign Research's gold seal certification and its MRIA membership to attempt to convince the Canadian public that Campaign Research did nothing wrong in carrying out the voter identification project in Mount Royal," the panel said, calling that a "blatant contravention" of the code.

The controversy prompted the MRIA earlier this year to update its code of conduct to spell out that voter identification or partisan promotion can not be conducted under the guise of market research.

Kouvalis has publicly boasted about his company's partisanship.

"We're in the business of getting Conservatives elected and ending Liberal careers," he was quoted as saying in December 2011. "We're good at it."

The panel said the Mount Royal poll was actually conducted by a division of Campaign Research, Campaign Support, although Kouvalis did not, in defending the poll, make any distinction.

Since then, Campaign Support has been established as a separate legal entity.