The Federal Communications Commission (FCC), the US telecoms regulator, is concerned AT&T’s DirecTV Now, a subscription video service which does not carry a data access charge, could be anti-competitive.

The US regulator told AT&T in a letter seen by Reuters that its video service and accompanying zero-rated app “may obstruct competition and harm consumers” because it could be too expensive for rivals not affiliated with the operator to sponsor the data cost needed to compete.

The operator has until 21 November to respond to the watchdog’s concerns.

DirecTV Now will cost $35 per month, including the cost of streaming content over AT&T’s network. The service is aimed at users who are not interested in conventional pay-TV subscriptions and is due to launch next month.

However, the service may breach the 2015 Net Neutrality rules, said the FCC.

Bob Quinn, AT&T’s senior executive vice president, responded in a statement that the operator will treat rivals equally: “We welcome any video provider that wishes to sponsor its content in the same ‘data free’ way for AT&T Mobility customers and we’ll do so on equal terms at our lowest wholesale rates”.

But the FCC letter from wireless telecommunication bureau chief Jon Wilkins said any potential rivals wanting to replicate the DirecTV Now service would face potential higher costs. These would include “overage fees and or reduced transmission fees” if subscribers exceeded allowances under their plan.