Minnesota Senator Al Franken, chairman of the US Senate Judiciary Subcommittee on Privacy, Technology and the Law, announced Monday he had scheduled a mobile privacy hearing for May 10 and had asked Google and Apple representatives to speak at the hearing.

"This hearing is the first step in making certain that federal laws protecting consumers' privacy - particularly when it comes to mobile devices - keep pace with advances in technology," Franken said in a statement.

Two iPhone users have filed a class action suit in Tampa, Florida, accusing Apple of invasion of privacy and computer fraud and seeking a judge's order to bar the alleged data collection.

Apple is also reportedly being investigated by South Korea, France, Germany and Italy over the alleged practice.

Worries on the iPhone tracking issue surfaced last Wednesday when two British researchers announced at a technology conference in California that iPhone has been collecting users' location information and storing the data since June 21, 2010.

Last Friday, The Wall Street Journal reported its security analysts had found that Apple's iPhone and smartphones running Google's Android operating system regularly transmit users' locations back to the two companies, which was part of their race to build databases capable of pinpointing people's locations via smartphones.

The newspaper reported on Sunday its analysts had also found iPhones were collecting and storing users' location data even when location services were turned off.

Google responded to the reports last Friday by saying that "all location sharing on Android is opt-in by the user."

"We provide users with notice and control over the collection, sharing and use of location in order to provide a better mobile experience on Android devices. Any location data that is sent back to Google location servers is anonymous and is not tied or traceable to a specific user," the company said in a statement.

Apple so far has refrained from commenting on the issue. Jobs reportedly responded to the matter Monday when replying to a reader email from MacRumors, a website aggregating Apple-related news.

"We don't track anyone. The info circulating around is false," the website quoted Jobs' email as saying.