Google has been ordered to pay millions of dollars in fines in the US after it tracked users of Apple's iPhone, iPad and Safari browser.
The Federal Trade Commission ordered Google to pay $22.5m, or £14.4m) for circumventing privacy protections on the mobile and desktop browser.
The fine is the largest ever paid to the FTC by a single company.
Google did not admit to any wrongdoing as part of the settlement.
FTC Chairman Jon Leibowitz said in a statement that Google had bypassed a 'do not track' setting in the browser, letting its cookies be installed via adverts even if users had opted out.
Cookies are small files which are used to collect information about a user's computer, and be used to help display ads based on that information.
The FTC charged Google with placing cookies within ads in 2011 and 2012.
The practice had been initially revealed by Jonathan Mayer, a researcher at Stanford University, who showed how the DoubleClick network was circumventing safeguards in mobile and desktop Safari.
In a statement the FTC said that it was sending a "clear message" that companies had to keep its promises on privacy.
"The record setting penalty in this matter sends a clear message to all companies under an FTC privacy order," said Jon Leibowitz, chairman of the FTC.
"No matter how big or small, all companies must abide by FTC orders against them and keep their privacy promises to consumers, or they will end up paying many times what it would have cost to comply in the first place."
Google said in a statement: "We set the highest standards of privacy and security for our users. The FTC is focused on a 2009 help center page published more than two years before our consent decree, and a year before Apple changed its cookie-handling policy. We have now changed that page and taken steps to remove the ad cookies, which collected no personal information, from Apple's browsers."
Meanwhile the privacy non-profit Big Brother Watch said Google's actions had set "a very dangerous precedent".
They told the Guardian: "We welcome this ruling as an important milestone in returning to consumers true control over their personal information.
"As we have often warned, where businesses rely on personal information to offer better targeted advertisements there will be inherent tension between respecting consumer privacy and pursuing profit."