PARIS — What does Google know about its users and how does it know it? European privacy regulators on Tuesday warned the company to clarify those issues — or risk fines or other penalties by early next year.
Google collects personal data, like the sex and age of users and their Web browsing histories, in order to tailor its services to individual users and also to sell ads.
In keeping with European privacy law, Google said it was collecting the data only if users ‘‘opted in.’’ But opting in essentially became a requirement of using each of the services after the new policy went into effect.
Regulators said Google provided users with incomplete disclosure about its processing and storage of the data.
European privacy regulators had expressed concern last winter about the new procedures and had asked Google to delay implementing them. After the company declined, the European Commission asked France’s privacy agency to take the lead on a legal analysis, which resulted in the warning to Page Tuesday.
The privacy regulators said Google provided users with incomplete disclosure about its processing and storage of the data, as well as insufficient control over how information from different Google services is blended to build detailed personal profiles.
Google also makes it too cumbersome for users to block the collection of these data, the regulators said.
Falque-Pierrotin, whose agency, called CNIL, conducted an investigation of the policy change on behalf of the other EU data-protection authorities, said she would give Google ‘‘three to four months’’ to make changes.
Google said it was reviewing the letter and an accompanying report from the data-protection authorities, but added that it was confident the new policy respected EU law.