"Personalized search does raise privacy issues," Fleischer wrote earlier this year in the Financial Times. "In order for it to work, search engines must have access to your Web search history. And there are some people who may not want to share that information because they believe it is too personal. For them, the improved results that personalized search brings are not matched by the 'cost' of revealing their Web history."
Fleischer argued that Google can handle this privacy issue by asking users if they want to opt in to the service when they open an account.
Google uses the information gathered from users' search histories for marketing purposes.
Tom Espiner of ZDNet UK reported from London.