The EU body, made up of national protection supervisors of the bloc's 27 member states, said earlier this year that Google seemed to be failing to respect EU privacy and expanded its investigation in June to other Web search engines.
"We have written to Google to say that we are continuing our work, that it is not limited to Google, and that we will adopt an opinion at the beginning of 2008," the official said after the so-called Article 29 committee met on Wednesday.
"We want to adopt a comprehensive opinion, saying how long they can keep data, and which ones," the official said.
When users carry out searches, Google gathers information about their tastes, interests and beliefs that could potentially be used by third parties such as advertisers, but the company says it never passes on the data.
Google wrote to the EU data watchdog in June saying the company was ready to curtail the time it stored user data to a year and a half.
That storage time was the low end of an 18- to 24-month period it had originally proposed to regulators in March.
The best-known search providers include Google, Yahoo, Microsoft's Live Search and Ask.com, which is owned by IAC/InterActiveCorp.
The watchdog advises the EU on privacy rules. It has no legal power and its opinions are not binding.






