Google has defended a policy of retaining data on web users for up to 18 months as necessary to improve search results.
The company was responding to an EU report that saw no need for search services to keep personal data beyond six months.
The long-anticipated set of recommendations for how European data protection laws should be applied to web search services was published on Friday. The report by the Article 29 Working Party calls for increased user notification and warns web search services that failing to do so may be unlawful.
But in a statement, Peter Fleischer, Google's global privacy counsel, said his company disagreed with key findings in the report and argued that privacy policies must be balanced against efforts to make web services easier to use.
"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," Mr Fleischer said.
The group of EU data protection commissioners found that computer web addresses and cookies are personal information that search services should do more to protect.
Cookies are small bits of text that mark the comings and goings of computer users to websites. They are widely used by commercial sites to make web surfing more convenient and by advertisers to measure audiences. But they also raise privacy concerns due to their potential to track user behaviour.
"It is the opinion of the working party that 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 states. "The working party does not see a basis for a retention period beyond six months," the EU study concluded.
The EU report can be found at http://tinyurl.com/5yukzm.