WASHINGTON — Google on Tuesday explained to a congressional panel how it protects users of its Android system for mobile devices from invasions of privacy, in response to worries about how those devices store location data.

Alan Davidson, Google’s director of public policy, told a newly created Senate Judiciary subcommittee on privacy and technology that so-called “location-sharing” data on the Android operating system was “strictly opt-in for our users, with clear notice and control.”

Davidson and Apple’s software chief were called to testify at the subcommittee hearing following an April 20 report by researchers that the operating system on Apple’s iPhone stores data about the location of the device as well as a time stamp. The Wall Street Journal also reported that Android phones were transmitting location-related data to Google several times an hour, even when location apps were not being used.

Lawmakers are now considering whether federal legislation is needed to protect consumers’ privacy on mobile devices. Sen. John Rockefeller (D-W.Va.) introduced an online “do not track” privacy bill Monday.

Apple’s testimony was not immediately available. Last week, Apple released an operating system update that reduces the amount of location data stored on an iPhone, and makes other privacy fixes.

Sen. Al Franken (D-Minn.) said in a letter to Apple CEO Steve Jobs on April 20 that the researchers’ report raised “serious privacy concerns.”

In prepared testimony, Google’s Davidson said the company has seen an “explosion in demand” for location-based services that allow users to avoid traffic jams, find local movie times and search out a nearby coffee shop among other examples.

Google does not collect any users’ location information on Android devices “unless the user specifically chooses to share this information with Google,” he added.

For more on this story, please go to MarketWatch.