OTTAWA -- Criminal charges have been laid against Irving Oil and a senior company executive for alleged price-fixing at gas stations in three Quebec cities.

The federal Competition Bureau says three charges of conspiracy are being laid against the New Brunswick-based company.

And the same three charges are also being laid against Serge Parent, the company's manager for Quebec.

The scheme allegedly took place in Victoriaville, Thetford Mines and Sherbrooke.

The federal bureau says it uncovered the plan using investigative tools, including wiretaps and searches.

It says it found evidence of gas retailers, or their representatives, communicating with each other to agree on the price they should charge at the pumps.

Thirty-nine people and 15 companies have been charged so far as a result of the Competition Bureau's ongoing investigations into gasoline price-fixing.

Twenty-seven people and seven of the companies have pleaded guilty, triggering fines totalling $3 million and short prison sentences for most of the individuals.