Two of the UK's leading broadband providers have urged Ofcom to separate BT from its infrastructure division Openreach.
As the media regulator begins an "overarching" review of the UK telecoms market, Sky and TalkTalk have called for decisive action to safeguard competition.
BT's takeover of EE - the UK's largest 4G broadband provider - has exacerbated fears about the firm's dominant market position, reports the Financial Times.
The planned acquisition will see BT control over one-third of the consumer telecoms market, and 70 per cent of the wholesale segment.
Dido Harding, Chief Executive at TalkTalk, said it is "crucial" that Ofcom seizes the opportunity to structurally separate BT from Openreach - a company created in 2005 to offer equal access to BT's network for all providers.
"A decade ago, Ofcom failed to break up BT and instead created Openreach. Whilst the last ten years have seen a lowering of prices and increased take-up, it is increasingly clear that the current market structure is not fit-for-purpose," she claimed.
"BT’s proposed merger with EE threatens to make a bad situation worse. It will further starve Openreach of the focus and capital it needs and will extend BT’s dominance of the market."
Ms Harding said a fully independent Openreach, focused exclusively on infrastructure, would be incentivised to maximise coverage and improve quality of service for customers.
She claimed this would end BT’s ability to erode competition, stimulating innovation, consumer choice and lower prices.
The TalkTalk CEO added that separation would accelerate investment in Britain’s digital infrastructure as other providers will have the "level playing field" they need to build competing infrastructure.
Jeremy Darroch, Chief Executive at Sky, echoed these comments, saying there are "serious questions" about whether the existing UK telecoms structure can deliver the infrastructure, innovation and choice that consumers and businesses need.
"Structural separation of Openreach, the UK's only nationwide broadband infrastructure, is at the heart of creating a sustainable industry," he stated.
Mr Darroch said this would be one that provides the capacity and incentive to invest, while also harnessing the power of multiple competing retailers to drive higher take-up and lower prices.
"Ofcom must now take the opportunity to address Openreach’s conflict of interest as a subsidiary of BT or risk extending the problems that are affecting the industry and its customers today," he added.