Representatives of the CTIA, a trade group representing mobile carriers, and the Association for Competitive Technology, a trade group representing mobile app developers, weren't immediately available for comment on the GAO report.

The report recommended that the U.S. Federal Trade Commission issue comprehensive guidance to mobile companies about location data privacy. The U.S. National Telecommunications and Information Administration (NTIA), which launched a series of multistakeholder privacy meetings this year, has not set performance goals for the process and lacks a mechanism to enforce any privacy recommendations created in the process, the report said.

The GAO report's authors looked at the privacy practices of 14 mobile companies, with 11 of the 14 being carriers, operating-system developers or app developers. Ten of the 11 disclosed that they used customers' location data, but many policies were "not clear," the report said.

Four of the companies described ways they used personal data, but did not say whether they consider location data to be personal data, the report said.

The IDG News Service