An EU report finding that search companies have no need to retain personal data for more than six months has been rejected by Google.

The report from the Article 29 Working Party (made up of national privacy commissioners from all 27 EU member states) said that search companies should do more to protect browsers' anonymity.

Search companies have maintained that information is kept for up to 18 months to help make a user's browsing experience more relevant – and target advertising more effectively.

"Search engines in their role as collectors of user data have so far insufficiently explained the nature and purpose of their operations to the users of their services," the report says.

"The Working Party does not see a basis for a retention period beyond 6 months."

Google – which recently reduced it's retention period from 24 to 18 months – took issue with the group's findings.

In a blog posting today, Google's lawyer Peter Fleischer says that the reason his firm is so successful today is active use of user information – a success that indicates customer satisfaction.

"We believe that data retention requirements have to take into account the need to provide quality products and services for users, like accurate search results, as well as system security and integrity concerns," he wrote.

Microsoft, which also has an 18 month retention policy and Yahoo, which keeps data for 13 months, have yet to comment.

Should the search engines fail to adopt the recommendations the Article 29 Working Party will consider pushing for the EU to adopt legislation restricting search data retention to its recommended level.