Vague privacy policies are making it hard for consumers to protect their location and other information collected by mobile devices, according to a Government Accountability Office report released Thursday.

"Companies GAO examined disclosed in their privacy policies that the companies were collecting consumers' location data, but did not clearly state how the companies were using these data or what third parties they may share them with," GAO investigators wrote. "Furthermore, although policies stated that companies shared location data with third parties, they were sometimes vague about which types of companies these were and why they were sharing the data."

Without clear information on exactly how companies use information, consumers "would be unable to effectively judge whether the uses of their location data might violate their privacy," the report concludes.

The report urges federal action, but its only specific recommendations are that Commerce Department officials set concrete goals for their effort to work with companies and consumer advocates to develop voluntary privacy standards. It also urges the Federal Trade Commission to outline its views on mobile location-data privacy.

Lawmakers pointed to the report as evidence that legislation is needed to prevent companies from abusing location-based data.

"I believe Americans have a fundamental right to privacy: to know what information is being collected about them and to be able to control whether or not that information is shared with third parties," Sen. Al Franken, D-Minn., chairman of the Senate Judiciary Subcommittee on Privacy, Technology, and the Law, said in a statement. His Location Privacy Protection Act would require companies to ask permission before they gather or share location information.

Rep. Ed Markey, D-Mass., co-chairman of the Bipartisan Congressional Privacy Caucus, also plugged his Mobile Device Privacy Act, which would establish privacy enforcement regimes for federal regulators; and require disclosure and permission before software can be downloaded, or begin collecting or sharing location information.

"In the 21st century, a mobile phone isn't just capturing who we call and what we say, it is also transmitting where we are,' Markey said in a statement. "I welcome the GAO's recommendation of strong federal rules for mobile phone companies to help protect customers from having their locations shared with third parties without their knowledge or consent."