Canada's privacy commissioner is considering a new investigation into Facebook applications after a report found several popular applications were sending personal user information to ad and internet tracking companies.

Jennifer Stoddart, Canada's privacy commissioner, is considering a new investigation into Facebook privacy after news that several applications gave private user information to marketing and tracking firms. (Adrian Wyld/Canadian Press)"If applications covered by [privacy law] are disclosing personal information without consent, that's a significant concern to our office," the office of Jennifer Stoddart said in a statement Monday to CBC News.

"We are looking at the situation and evaluating the possibility of launching an investigation."

About 12 million Canadians and more than 500 million people worldwide are Facebook users.

The privacy breach was revealed in an investigation by the Wall Street Journal, which found at least 10 of the most popular Facebook applications were sending the ID numbers of the social networking site's users to at least 25 advertising, marketing and internet tracking firms.

Among the largest of the reported breaches came from game-maker Zynga which produces apps such as FarmVille, with 59 million users, as well as Texas HoldEm Poker, FrontierVille and Mafia Wars.

Applications — links that enable Facebook users to play games, purchase gifts, join causes and more — are not produced by Facebook. They're created by outside developers, such as Zynga.

The San Francisco-based games developer has not responded to an interview request from CBC News.

Breach 'not intentional': Facebook

In a Facebook developer's blog post, Mike Vernal, a member of the Facebook platform engineering team, said the privacy breach was not intentional.

"In most cases, developers did not intend to pass on this information, but did so because of the technical details of how browsers work."

Some Facebook applications have been transmitting personal data to advertising and tracking companies, according to the Wall Street Journal. (Canadian Press)He said press reports have overstated the implications of sharing a Facebook user's ID number, saying it would not allow anyone to access private user information without consent.

The website forbids companies providing applications from transferring user data to outside ad and tracking agencies.

Facebook changed its site earlier this year, to enhance user privacy, after a being reprimanded by Stoddart. On Sept. 22, she announced she was satisfied with the changes made by Facebook.

According to the Journal's investigation, the applications were recording each user's individual Facebook ID number, which the newspaper said could be used to access their personal information, regardless of their privacy settings.

Facebook applications that shared users' private information also include:

• Phrases.
• Treasure Isle.
• Quiz Planet.
• Cafe World.