South Korean police said they raided Google Inc's Seoul office on Tuesday on suspicion that the Internet search leader had illegally collected data on users.
Google has been preparing since late last year to launch its "Street View" service in South Korea and the data collection was related to the launch, police said.
The probe in one of Asia's most wired countries came as a fresh setback to Google, which already faces investigation over "Street View" by the U.S. Federal Trade Commission, a variety of probes overseas and class action lawsuits.
Google was not immediately available for comment.
"(The police) have been investigating Google Korea LLC on suspicion of unauthorized collection and storage of data on unspecified Internet users from Wi-Fi networks," the Korean National Police Agency said in a statement.
Google has said previously the data was accidentally collected by its cars and has grounded its "Street View" cars globally.
Google Street View is a technology featured in Google Maps and Google Earth that provides panoramic views from various positions along many streets in the world.