A European Union probe triggered by concerns over how long Google stores user information has widened to include all Internet search engines.
The EU's panel of national data protection officers said it's now concerned over the retention of data that the companies use to deliver more relevant search results and advertising. Some fear the data could be targeted by hackers and governments.
"The Working Party will deal with search engines in general and scrutinize their activities from a data-protection point of view, because this issue affects an ever-growing number of users," it said in a statement Thursday.
Trying to soothe EU concerns, Google this month offered to cut the time it retains data on user searches from the current 24 months to 18 months, saying this was going further than most other search engines. After that, identifying information is removed.
It insists that its retention policies comply with EU data privacy rules.
The 28-member panel, which advises the European Commission and EU governments on data protection issues, said it still needed to analyze Google's response and would also look at other search engines in the coming weeks to evaluate what data protection issues were at stake.
It also has asked Google to answer questions on the specific use of technologies used by Google and other Web sites to collect insights about what sites people visit.
The EU investigation into Google comes amid growing concerns over the Mountain View, Calif.-based company's privacy practices.
London-based Privacy International has rated Google the worst among the Internet's top destinations on privacy.
The watchdog said it was particularly troubled by Google's ability to match data gathered by its search engine with information collected from other services such as e-mail, instant messaging and maps.
