Blaming the Conservatives for the growing "robocall" scandal is just an NDP and Liberal "smear campaign," Prime Minister Stephen Harper told the House of Commons Wednesday.

The Conservative Party "absolutely and definitely" had nothing to do with phone calls that allegedly aimed to confuse and harass voters in the last federal election, Harper said.

Elections Canada and the RCMP are investigating reports of automated calls in up to 18 ridings that incorrectly told voters their polling stations had been changed.

CTV News has confirmed that the RCMP has also contacted some employees of a Thunder Bay call centre, Responsive Marketing Group Inc. Investigators will be in the city next week to ask those employees questions about their work for the Conservative Party in the last election.

In a statement, RMG said, "We have not been contacted by Elections Canada, but will be contacting the agency to offer our full cooperation. RMG has done nothing wrong, and an (Elections Canada) investigation will confirm this."

Opposition parties now say they've received complaints about election-related phone calls from voters in 61 ridings across Canada. They also say some of their supporters got live "antagonizing" phone calls, often late at night.

In a Guelph, Ont., riding, voters reported getting calls from a phone number with a 450 area code, directing them to the wrong polling station. Court documents show that number was linked to a disposable or "burner" cellphone registered to a "Pierre Poutine" from "Separatist Street" in Joliette, Que. -- an obviously fake identity.

The opposition alleges the phone calls aimed to suppress Liberal and NDP votes and may have affected election day outcomes in some ridings.

Green Party Leader Elizabeth May also said her Saanich-Gulf Islands riding was hit by "robocalls."

But the Conservatives said their supporters were targeted by unusual phone calls as well last year. Tory MP Dean Del Mastro claims his campaign volunteers and supporters received harassing and "rude" calls leading up to the election.

During question period Wednesday, the Conservatives said opposition parties were simply being sore losers and blowing the calls out of proportion.

In statement to CTV News, a young Tory staffer who resigned amidst the robocall scandal said he had no involvement with any fraudulent calls.

Michael Sona, 23, said he was not responsible for the calls, but had to resign from Conservative MP Eve Adams's office because of all the speculation and negative attention. He said he hopes the real culprit will come forward.

In court documents, Elections Canada's chief investigator Al Mathews said whoever was using the fake "Pierre Poutine" name wanted to make sure his or her tracks were covered.

Phone records show the number registered to Pierre Poutine twice called Edmonton-based call centre RackNine Inc., on April 30 and May 1.

The records also show phones associated with Guelph Conservative candidate Marty Burke and the Guelph Conservative riding association made a total of 31 calls to RackNine between March 26 and early May.

In the court documents, Mathews says there is reason to believe that Burke did business with RackNine and that the relationship is connected with the phony calls. The claims have not been proven in court.

RackNine has said that an unknown person used its automatic dialing service, and it's doing all it can to help with the probe. The company is not suspected of having committed any offences and is not subject to the investigation.

With files from The Canadian Press