France, Germany, Italy, the Netherlands, Spain and Britain said they had begun a process to decide if Google's policy introduced in March 2012 broke national laws.
Google consolidated 60 privacy policies into one last year and started combining data collected on individual users across its services, such as YouTube, Gmail and the social network Google+. It gave the users no means to opt out.
Twenty-nine European data protection regulators began a joint inquiry as a result. In October the inquiry, led by France's CNIL, found that Google's new policy posed a "high risk" to the privacy of individuals, although it stopped short of declaring it illegal.
"Regulators in six states have begun the process of looking at penalties, and each must now act based on national law," said Isabelle Falque-Pierrotin, CNIL's president. "We have put in place a countdown for Google now. Promises to change will no longer be enough."