Viviane Reding, the EU Justice Commissioner, told the Financial Times Google's decision to go ahead with the new privacy policies was unfortunate when it was not clear that these complied with European law. She said she backed a call by French regulators to delay implementation.
Battle lines between European governments and the US internet search company have been hardening over its business practices. The European Commission is expected to rule later this month on whether Google has breached antitrust laws in the way it operates its search service. French judges have ruled this year in separate cases that Google abused its dominance in the online mapping market and in its AdWords advertising service.
The new privacy rules make it possible for Google to take what it has learnt about a user from one of its services â€“ such as search or Gmail â€“ and use it to tailor what that user sees on other services. The content of emails sent using Gmail might, for example, influence what advertising is shown to that person on YouTube. France's data protection agency, the CNIL, warned this week that European regulators had "strong doubts about the lawfulness and fairness" of this use of personal data.
Google said it complies with local laws. The changes would result in a better experience for users, for example, by using the information to provide more relevant search results, it said.
"Our approach to privacy isn't changing," Alma Whitten, Google's director of privacy, wrote in an article that appeared on several European news sites. "We're not collecting any new information as a result of this change. We're not altering any of your privacy settings. And we still won't sell your personal information to advertisers. We just want to use the information you already trust us with to make your experience better."
The Japanese government has also written to Google to express its concern about its handling of personal data.
Last month, the Electronic Frontier Foundation, a campaigner for internet freedoms in the US, suggested supporters should delete some of the information that Google keeps about historical search queries, before the changes came into effect.
Google has run an extensive campaign ahead of the changes, including prominent warnings across its sites and services.
However, regulators remain concerned about the privacy of hundreds of millions of users and the growing targeting of advertising across Google's full online reach. "Google should be congratulated on doing some things well. They do allow people to use the services when they are not logged in," said Gus Hosein of Privacy International, a campaign group. "However, we need more detail on what they are doing with the data.
How long are they keeping it? Who are they sharing it with?"
Mr Hosein said that users were "being left in the dirt" amid an online power struggle between Google and its younger rival, Facebook, as both seek to increase their share of customers' time and data, and advertising spending.
Internet companies are preparing to fight back against new privacy laws which the European Union put forward in January. The UK's Direct Marketing Association, a trade body, is preparing a study stressing the wider economic contribution of the data-based advertising industry.
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