The Competition Bureau of Canada says it is investigating fuel prices in northwestern Ontario after Ontario's energy minister and Kenora-area MPP Greg Rickford called for a probe last month.

Rickford said the region has long been subject to higher-than-average prices at the pumps but added that he took particular notice when the PC government scrapped the provincial carbon tax and prices hadn't dropped in the northwest like he said they had elsewhere in Ontario.

"This is a very serious matter," Rickford told CBC News. "While I'm trilled in a sense that it's being done, it's most unfortunate that it's actually happened."

The government has said that the elimination of the carbon tax equalled taking 4.3 cents per-litre off the wholesale price of gasoline. That wasn't being reflected in the north, Rickford said.

"The rest of the province retail margin prices were dropping and the carbon tax had been taken off," he said. "None of it had come off out in northwestern Ontario."

Energy Minister - and Kenora-area MPP - Greg Rickford called for the business watchdog to take a look at why gas prices in northwestern Ontario remain high. (Adrian Wyld/Canadian Press) "That's without explanation, it may be obvious why it's come down [elsewhere] but we want to know why it's coming down and we're going to find out."

The federal Competition Act prohibits "price-fixing, competitor collaborations, price maintenance and abuse of dominant position," according to a letter sent to Rickford by Matthew Boswell, the bureau's interim commissioner of competition. It added that the watchdog is "taking further steps to examine the situation in northwestern Ontario," including contacting industry participants.

"I have every bit of confidence that they're going to take a comprehensive look at retailers, price-fixing is on the table," Rickford said, adding that he expects the probe will also examine "a whole host of other pieces that they'll be taking a look at industry-wide and start explaining to us why the prices have been so high."

Rickford said he's seen discrepancies in the price at the pump of as much as 20 to 30 cents per-litre between Kenora and Winnipeg. He also referenced the government's campaign promise to reduce gas prices by 10 cents per litre.

"If we don't get this fixed ... how can we take another five cents off the price per litre of gasoline that somebody, somewhere in the retail margins of the cost of a litre of gasoline could just take up?"

Rickford said he also hopes the investigation will bring more public awareness to how the price-per-litre at the pump is actually calculated and better inform the province as to how government can play a role in bringing that cost down.

Other investigations have led to charges, watchdog says

The competition bureau told CBC News that it has done several other investigations into the price at the pump in a number of markets in Ontario and Quebec since 2008.

"Those investigations have resulted in several individuals and a plurality of companies pleading guilty or being found guilty of price fixing," said Pierre-Yves Guay, the acting associate deputy commissioner of the agency's cartels directorate.

"I can tell you that the competition bureau recognizes that gasoline prices are an important issue for Canadians."

Guay added that, by law, the bureau can't speak to the details of an ongoing investigation. Its findings, if appropriate, are shared with the Public Prosecution Service of Canada for consideration of charges under the Competition Act.

Rickford added that he will reach out again to the business watchdog for more information about the investigation in the northwest, including exactly how long it is expected to take; Rickford said, at this point, his sense is that the probe will take a couple of months.

Guay said he couldn't say how long the probe would take.