Apple's iPhones and Google's Android phones send back data about the locations of the users to the technology companies, the Wall Street Journal reported on Thursday.
These phones regularly transmit such data to Apple and Google as the two build databases that could help them tap a market for location-based services, the Journal reported, citing data and documents it had analyzed.
The paper cited a research by security analyst Samy Kamkar that said the HTC Android phone sent such information several times every hour after collecting the data every few seconds.
Google and Apple were not immediately available for comment to Reuters late on Thursday.
The phone also sent information about wireless Internet networks in the area, the paper said.
The iPhone transmits data about the user's location and Wi-Fi networks to itself every 12 hours, the paper said.