The US Federal Communications Commission (FCC) will not investigate Netflix for reducing the quality of video it delivers on the mobile networks of operators including AT&T and Verizon, reported Reuters.

The video provider said last week it had been “throttling” the video streams delivered “to most wireless carriers across the globe”, including AT&T and Verizon, for more than five years, because of data caps.

However, Netflix’s conduct is “outside” the FCC’s net neutrality rules, which were adopted last year, said chairman Tom Wheeler, adding that FCC is not regulating “edge providers” or websites – its focus is the networks over which services are delivered.

Netflix’s admission led to a furious reaction from AT&T in particular, with senior executive vice president Jim Cicconi stating the company was “outraged” to learn that Netflix is throttling video for its customers without their knowledge or consent.

Verizon, meanwhile said it doesn’t throttle or manipulate video content itself. “We deliver video content at the resolution provided by the host service, whether that’s Netflix or any other provider,” said a spokesman to Wall Street Journal, which broke the original story.

Netflix, an outspoken supporter of net neutrality, added it did not limit video quality for the US’ two other operators, T-Mobile US and Sprint, because “historically those two companies have had more consumer friendly policy”.

Video quality is however reduced on T-Mobile US’ networks when customers have activated the company’s video streaming service Binge On.

Critics have also said that Netflix should have been more transparent in its interventions to the FCC’s net neutrality debate, bearing in mind its own mixed approach to traffic management.

Speaking to Reuters, executive director of advocacy group Consumer Action, Ken McEldowney claimed Netflix had demonstrated “a complete lack of transparency with customers”, but said the news was confusing because Netflix settings had also allowed its users to choose their own preference, whether it is picture quality or data usage.

“Most consumers that encounter video playback issues are likely to unfairly place the blame on their broadband providers,” he added.