The Federal Trade Commission and European regulators are investigating Google for violating the online privacy choices of consumers using the Safari web browser on Apple computers, iPhones and iPads.

A recent study by Jonathan Mayer of Stanford University's Security Lab, and the Center for Internet and Society, found that Google has been circumventing a privacy setting in Apple's Safari web browser. Like most web browsers, Safari provides the option not to receive third-party "cookies." Blocking third-party cookies is supposed to prevent such tracking. Safari is the primary browser on the iPhone and iPad.

Google has developed a so-called browser "plugin" for Internet Explorer, Firefox and Google Chrome that makes the opt-out persistent. Google has not developed a plugin for Safari. The advice Google gave Safari users follows:

"While we don't yet have a Safari version of the Google advertising cookie opt-out plugin, Safari is set by default to block all third-party cookies. If you have not changed those settings, this option effectively accomplishes the same thing as setting the opt-out cookie."

Later Google said it would will cooperate with any investigations.

"We will of course cooperate with any officials who have questions," said Chris Gaither, a spokesman for Google, which has acknowledged it placed the advertising cookies on Safari after opening a connection to give signed-in users access to a Google function. "But it's important to remember that we didn't anticipate this would happen."

European regulators are already reviewing Google's new privacy policy, which was put in place March 1 to streamline privacy settings for its services and products.