An £830m plan to bring superfast broadband to every community in the UK by 2015 could be in jeopardy, after a leaked letter revealed ISPs including TalkTalk and Virgin Media are unhappy about the prices and terms and conditions imposed by BT on other providers to use its existing ducts and poles.

In October last year, Ofcom gave a proposal known as 'virtual unbundling' the go-ahead. The proposal was initially unveiled in March 2010 and will see UK ISPs using BT's infrastructure to offer their own superfast net connections, rather than laying their own fibre-optic cables.

However, in the letter to Ed Vaizey - the minister for culture, communications and the creative industries, who also heads Broadband Delivery UK (BDUK), the body that has been tasked with overseeing the roll-out of superfast broadband across the UK - the firms said they are "unanimous in the belief that the BDUK competitive procurement process will lack a credible alternative to BT, should BT fail to make substantial revisions to PIA [physical infrastructure access] product pricing".

The letter, which was seen by Computer Weekly and also signed by Fujitsu, Geo and Vtesse Networks, called for "urgent intervention" in regards to the pricing structure set by BT.

"Without this, we believe that the BDUK process risks a lack of vigorous competition and as a result, will fail to deliver the investment, quality, speed of roll-out, innovation and value for money, that industry is capable of delivering and that taxpayers deserve," it stated.

BT said its proposed prices for duct access "compare very well with European averages, whilst our plans for pole access have been held up due to others delaying our trials.

"Once those trials are underway we will be in a far better position to understand the costs involved and so we would encourage these companies to start trialling with us as soon as possible."

Ofcom said it was "talking to BT" in a bid to understand how the pricing structure was determined.