The government programme to roll out superfast broadband to 90% of the population is running late and lacks strong competition to protect public value, the National Audit Office has reported.
The government has already announced that superfast broadband will reach 95% of the population by 2017, two years after the original target of reaching 90% by 2015.
Just nine out of 44 local projects are expected to reach the original target, according to the NAO report, with the delay partly attributed to the EU State Aid process taking six months longer than expected.
The NAO also said that competition among suppliers had been "limited", leaving BT as the only active participant and expected to win all 44 local projects.
It warned that the Department for Culture, Media and Sport had "secured only limited transparency" over the costs in BT's bids.
And it said the DCMS now expected BT to provide just 23% of the overall projected funding of £1.5 billion, some £207 million less than expected.
A BT spokesman said: "BT's fibre programme has been one of the most efficient in the world with the company going further and faster than industry experts thought possible.
"BT has applied these cost efficiencies to its Broadband Delivery UK work and so the company is delivering excellent value for money.
"There was strong competition when prices were set at the start of the process and that has ensured counties have benefited from the best possible terms.
"Deploying fibre broadband is an expensive long-term business and so it was no surprise that others dropped out as the going got tough.
Communications minister Ed Vaizey said the Government had "under-promised and are going to over-deliver" on the broadband programme, because it will connect 92% of homes on a budget originally intended to reach 90%.
Mr Vaizey told BBC Radio 4's Today: "We said we would do it by 2015. By the end of 2015, we will have delivered to 88%. By early 2016, we'll get to 90%, and by the end of the programme we will get to 92%.
"BT is delivering the fastest roll-out of superfast broadband anywhere in the world, with 100,000 premises being passed every week. Its commercial roll-out is 18 months ahead of schedule.
"With our own programme, we are going to exceed our target of 90%, we are going to get to 92% and we are investing an additional #250 million, which will get us to at least 95%."