U.S. legislators on Wednesday sought more information from Apple Inc regarding its privacy policies, pulling the iPhone manufacturer into a swelling controversy over how developers on its popular iOS mobile platform have been able to access users' private address book data.

In a letter addressed to Apple Chief Executive Tim Cook, Representatives Henry Waxman of California and G.K. Butterfield of North Carolina, both Democrats on the House Energy and Commerce Committee, asked Apple to clarify its developer guidelines and the measures taken by the company to screen apps that are sold on its App Store.

The letter comes after Path, a San Francisco startup that makes a Facebook-like social networking app, attracted widespread criticism last week after a Singaporean developer discovered that Path's iPhone app had been quietly uploading his contacts' names and phone numbers onto Path's servers.

In the following days, other technology bloggers discovered that iPhone apps like Facebook, Twitter, Foursquare and Foodspotting similarly uploads user data - without permission, in some cases.

The Path incident raises questions about whether Apple's iOS app developer policies and practices may fall short when it comes to protecting the information of iPhone users and their contacts, the letter said.

The legislators' request for information casts the spotlight squarely onto Apple for the first time since an independent blogger, Dustin Curtis, wrote in a widely distributed post last week that there's a quiet understanding among many iOS app developers that it is acceptable to send a user's entire address book, without their permission to remote servers and then store it for future reference.

Curtis blamed Apple, writing that he could not think of a rational reason for why Apple has not placed any protections on Address Book in iOS.

In their letter to Apple, Waxman and Butterfield, referenced Curtis' blog post, adding: There could be some truth to these claims.

The legislators requested Apple to submit its response by February 29.

Apple could not be immediately reached for comment.

(Reporting By Gerry Shih; Editing by Richard Chang)