Canada's Competition Bureau has again found no price fixing or collusion in gas station pump prices – the fifth time it's looked at the issue in the last 15 years.

"We found no evidence to suggest a national conspiracy by gasoline companies to coordinate price increases," competition commissioner Sheridan Scott said in a release.

"Retail gasoline pricing behaviour in major centres across Canada during this period was consistent with independent pricing actions taken by businesses in response to normal market forces."

The bureau found that low inventories of gasoline in North America and worldwide increases in the price of crude oil were responsible for the rapid rise in retail gas prices during the spring and summer of 2004.

After what it called a "thorough examination," the bureau found that once taxes were excluded, gas prices in Canada were lower than prices in most industrialized countries "and were slightly lower than prices in the United States in May 2004."

Since 1990, the Competition Bureau has carried out five major investigations into allegations of collusion or price fixing in the retail gasoline industry. It said it has always found "no evidence" to suggest that price increases were a result of a "conspiracy to limit competition in gasoline supply."