A draft government report on LightSquared's proposed LTE network leaked to the media on Friday shows the service knocked out 75 percent of GPS receivers studied in a recent test.
An early version of the report provided to Bloomberg found that "LightSquared signals caused harmful interference to the majority of GPS receivers tested."
LightSquared's mobile broadband ambitions have been held up by problems with GPS interference. The venture-backed company will not get regulatory permission to move forward with its plans until it solves the issue.
The report came the same week that LightSquared claimed independent tests showed it had fixed the problem, even for sensitive high-precision receivers.
LightSquared says it was "outraged" by the leak of what it characterized as "incomplete" government data.
"The statement that testing shows that most GPS devices would be disrupted by LightSquared's operation is patently false," said Martin Harriman, LightSquared's executive vice president of ecosystem development and satellite business.
Harriman claims the report overestimates the amount of power that will be emitted by LightSquared's base stations.
The report came out the same day that the SEC announced it was considering an investigation into LightSquared's primary backer, Philip Falcone's hedge fund Harbinger Capital Partners.
The financial regulator sent Harbinger a Wells notice, which indicates the SEC believes the firm may have violated securities laws and may file charges.
The SEC is looking into whether Harbinger agreed to let some clients withdraw their investments while barring others from pulling out, according to an unnamed source cited by The Wall Street Journal.