Interim Liberal Leader Bob Rae claims reports of "robocalls" and voter suppression tactics contributed to the defeat of Liberal candidates in at least 27 ridings during the last federal election.

These tactics were the equivalent of "stuffing a ballot box," Rae said at a news conference in the riding of Toronto-Danforth on Saturday.

Rae called on "the prime minister, any Conservative MP, candidate or party official" who has any knowledge of these reports to come forward and turn the information over to the RCMP or Elections Canada for investigation.

According to Rae, these reports are part of a wider misinformation campaign by the Conservatives and he is calling on Parliament to hold an emergency debate on Monday.

Both Rae and NDP Leader Nycole Turmel raised the controversy while campaigning in the byelection in Toronto-Danforth and vowed to keep the heat on the governing Conservatives.

Turmel said the scandal has eroded Canadians' faith in the electoral process and a thorough RCMP probe is necessary to restore credibility in the system.

In an interview with CBC News on Saturday, Dean Del Mastro, the parliamentary secretary to Prime Minister Stephen Harper, said his own campaign in Peterborough, Ont., was "the victim" of dirty tricks.

Del Mastro said he would be providing Elections Canada with this information and said the party is calling on anyone with any information about these fraudulent calls to do the same.

CBC News has learned that Jim Maloway, former NDP MP and the current member for Elmwood in the Manitoba legislature, has sent a letter to the chief electoral officer asking him to investigate "possible organized illegal activity" in the federal riding of Elmwood-Transcona.

Maloway ran for the federal NDP in the last election but lost to Conservative Lawrence Toet by less than 300 votes.

In an interview with CBC News, Maloway said six or seven calls were reported to his campaign from voters who said they received calls claiming to be from Elections Canada that redirected them to different polling stations.

While it's not unusual for political campaigns to use automated calls for legitimate campaigning, robocalls can also be used to frustrate voters into giving up on casting a ballot, a tactic referred to as voter suppression, which is illegal under the Canada Elections Act.

The Liberals and NDP are accusing the Conservatives of using "dirty tricks" in a scheme to suppress the vote in at least 34 tightly contested races in the last federal election campaign.

Their allegations follow an investigation by the Ottawa Citizen revealing that Elections Canada traced fraudulent calls to a call centre company in Edmonton called Racknine.

Nine Conservative campaigns used the services of Racknine during the last federal election campaign.

'Dirty tricks' spread beyond 'robocalls'

In addition to the fraudulent robocalls, an investigative story by PostMedia News-Ottawa Citizen published Saturday found that voters in 14 ridings also received fake live calls from people claiming to be representatives of the local Liberal candidate in the riding.

Liberals claim reports of "dirty tricks" included "aggressive people acting on behalf of the Conservative Party outside of polling stations misleading voters" to reports of "instant voters" who cast ballots in ridings where they did not actually reside.

In an interview with CBC Radio's The House, Rae told host Evan Solomon that former Liberal MP Joe Volpe, who ran and lost to Conservative Joe Oliver in the riding of Eglinton-Lawrence, "has affidavits from many people who received phone calls that pretended to be from the Liberal Party but clearly were not."

Rae also pointed to Liberal candidate Borys Wrzesnewskyj, who lost to Conservative Ted Opitz by less than 30 votes in the riding of Etobicoke Centre, saying "he has evidence of vote tampering and people being excluded from voting."

In an email to CBC News on Saturday, Conservative Party spokesperson Fred DeLorey called the allegations by the Liberal Party "unsubstantiated."

"We have always been available to co-operate with Elections Canada and will do so fully if asked."

"The Conservative Party of Canada ran a clean and ethical campaign and would never tolerate such activity. We call on Elections Canada to get to the bottom of this as soon as possible," wrote DeLorey.

The RCMP has confirmed the force is supporting Elections Canada in its investigation into the fraudulent robocalls.

Elections Canada

Also in an interview airing Saturday on CBC Radio's The House, former chief electoral officer Jean-Pierre Kingsley told Solomon, "I've never seen this kind of allegation, this kind of dirty tricks" before.

According to Kingsley, it is "essential" that Elections Canada finds out if this was a co-ordinated effort on the part of a party or simply the act of one or more individuals.

Stephen Maher, one of the reporters who broke the original story for PostMedia News, told CBC News on Saturday that "something happened to the benefit of Conservative campaigns. In order for it to happen, they had to have money, they had to have organization and they had to have voter lists."

Michael Sona, a 23-year-old Conservative staffer who worked for candidate Marty Burke in the riding of Guelph, Ont., during the last election, resigned Friday amid the investigation by Elections Canada into the fraudulent robocalls.

Voters in the riding of Guelph complained they were directed to the wrong polling station by automated calls claiming to be on behalf of Elections Canada.

CBC News reported last May 2, 2011 — the day of the federal election — that voters in Ontario, Manitoba and British Columbia were reporting fraudulent calls to Elections Canada. The fake calls directed voters in ridings across the country to the wrong or non-existent polling stations.

The NDP and Liberals say the list of provinces with ridings that received reports of misleading election-related calls now includes Ontario, Alberta, Manitoba, Nova Scotia and Prince Edward Island.

Both Turmel and Rae said the scheme was too broad and complex to stem from one lone agent.

"We don't believe one person did it alone. Too many ridings are affected by this," Turmel said.

With files from The Canadian Press