Lawmakers want answers from Apple after a report was published this week that showed that iPhones and iPads track and store users' location information.

Congressman Ed Markey, who is the co-chair of the House Bipartisan Privacy Caucus, sent a letter today to Apple CEO Steve Jobs in response to a report published yesterday by Alasdair Allan, senior research fellow in astronomy at the University of Exeter, and Pete Warden.

The researchers discovered that the iOS version 4 software for the iPad and iPhone creates a log file of where users have been, based on time stamps and location information. The information is stored locally on the devices without any encryption and it's transferred via iTunes to computers that these devices are synced to.

It's unclear what the data is used for or why Apple has been collecting it in iOS products that carry a 3G antenna for nearly a year now.

But Congressman Markey said in his letter that he wants some answers.

"Apple needs to safeguard the personal location information of its users to ensure that an iPhone doesn't become an iTrack," he said in a statement Thursday. "Collecting, storing, and disclosing a consumer's location for commercial purposes without their express permission is unacceptable and would violate current law. That's why I am requesting responses to these questions to better understand Apple's data collection and storage policies to make certain sensitive information can't be left behind for others to follow."

Specifically, Markey wants to know if Apple developed the feature intentionally to keep a log of users' whereabouts. And if it did mean to collect this information, what did it intend to do with it He also wants to know if Apple has notified consumers that this information is being collected.

If Apple did collect this data and intends to share it with marketers without users' consent, it could violate federal law, Markey said.

Apple has not responded to requests for comment on the report, nor has it responded to Markey's or other politicians' letters. Yesterday, Sen. Al Franken (D-Minn.) stated that "the existence of this information--stored in an unencrypted format--raises serious privacy concerns." And he wanted to know why this feature exists.

Rep. Jay Inslee (D-Wash.) also issued a statement that criticized Apple for not notifying customers that this information was being recorded and stored on their devices.

Markey is seeking an answer to his questions by May 12.