France's data privacy watchdog CNIL fined US tech titans Google and Amazon 135 million euros for placing advertising cookies on users' computers without consent.

The €100 million fine against Google is the largest sanction ever imposed by a regulator.

A cookie is a small piece of data stored on a user's computer that allows websites to identify users and remember their previous actions. They are important for delivering targeted advertising as well as improving the user experience on websites.

When a user visited the website google.fr, several cookies used for advertising purposes were automatically placed on the computer without any action required on the user's part, the CNIL said.

No matter which way the users took to visit the website, they were either insufficiently informed or never informed that cookies were placed on their computer, the regulator noted. The type of cookie used can only be placed after the user has expressed his consent, CNIL added.