SAN FRANCISCO - Apple Inc. and Google Inc. were facing mounting pressure Monday from US lawmakers and consumers after media reports highlighted their location-tracking practices.

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The US House Energy and Commerce Committee on Monday sent letters to six developers of mobile device operating systems, including Apple and Google, seeking more information on implications of such tracking for individual privacy and federal communications policy.

In the letter sent to Apple CEO Steve Jobs, the Committee asked him to respond to nine questions no later than May 9, including "What location data do devices running your operating system track, use, store or share?", "Why does the device track, use, store or share that data?", and "How is the data used, stored, or shared and how is it protected?"

Similar letters were also sent to Google, Nokia, Microsoft, Research In Motion and Hewlett Packard. Nokia said the location data it collected was only stored in the device, and sent or collected when the user chose to use such services. Other companies have made no comment on the letters yet.

Also on Monday, Illinois state Attorney General Lisa Madigan called for a meeting with Apple and Google executives on the location-tracking reports, citing her ongoing effort to protect consumers' personal information online.

"I want to know whether consumers have been informed of what is being tracked and stored by Apple and Google and whether those tracking and storage features can be disabled," Madigan said. "It's important that these companies ensure that their users' private information is protected."