BT has hit back at TalkTalk, which claimed last week the former national telecoms operator is establishing a fibre broadband monopoly.
Writing in the Telegraph, TalkTalk Chief Executive Dido Harding said the market for super-fast broadband is "fundamentally less competitive" than the copper equivalent, due to the high cost of using BT's wholesale network.
She claimed that by pricing fibre at a premium, BT is "driving up costs for families and businesses when they can least afford it".
A week later, BT has responded to the comments, accusing TalkTalk - which uses its wholesale network - of "special pleading and opportunism".
In his own letter to The Telegraph, John Petter, Chief Executive of BT Consumer, rejected Ms Harding's argument that Ofcom regulation is needed to increase fibre broadband competition.
"Dido Harding’s charge that prices for fibre-optic broadband prices are high is contradicted by Ofcom data that the UK has faster speeds and lower prices than other parts of Europe, as well as by the many low-priced offers available, such as our 'fibre for a fiver’ campaign," he stated.
"The claim that BT is 'slowing the spread of fibre broadband’ negates the £2.5 billion investment made by BT shareholders."
Mr Petter said BT is making "a major contribution" to the UK by building "a major piece of national infrastructure" that will benefit consumers and businesses for many years to come.
He added that a complaint from TalkTalk about a supposed 'margin squeeze' under competition law has already been rejected.
“As a keen jockey, it seems Harding’s argument has fallen at the first fence," Mr Petter wrote.
"The regulator, Ofcom, rejected her claims of anti-competitive margin squeeze behaviour and found BT innocent.”