Members of Congress are calling for inquiry into a report from two researchers yesterday who found a file in the iPhone that records time-stamped location data. The researchers, Pete Warden and Alasdair Allan, reported yesterday that they had found the unencrypted file in the iPhone and 3G iPad.

On Thursday, Rep. Ed Markey (D-Mass.), a member of the House Energy and Commerce committee, sent a letter to Apple asking the company to confirm that report and explain the functionality of the file by May 12.

Markey joins Sen. Al Franken (D-Minn.), who sent a quick letter to Apple on Wednesday expressing his concerns about the report and asking similar questions about the purpose of the file.

Both legislators raised particular concerns that the file seemed to collect the same information about all users, even those under 18.

Rep. Jay Inslee (D-Wash.) also issued a statement on the report, saying that he will ask Apple and federal agencies with oversight on privacy for more information on the file and how the information is used and shared.

Inslee also called for comprehensive privacy legislation to deal with issues such as this in the future.

“This episode, and many others, illustrates the need for enhanced government oversight of data collection activities,” he said. “As a result, I am working on comprehensive privacy legislation that will empower consumers with real information and protections against privacy violations.”

The data collection appears to be linked to Apple’s iOS 4 platform, and there is no indication that it is beng transmitted back to Apple or to third parties.

The Wall Street Journal reported Thursday that iPhones and Google’s Android smartphones regularly transmit their locations back to the companies as part of their efforts to build databases for future location-based services.