A committee of MPs said that many of the maps released lacked sufficient detail about coverage and the speeds that would be provided. It also questioned the costs involved.
It added that it had heard allegations that BT had been able to "kill the competition" by altering its own plans.
Both the company and the government have defended their record.
"It is... frustrating that the committee continues to try and pick holes in the programme," said a spokesman for the firm.
"BT is delivering value for money and the National Audit Office acknowledged there are 'robust' processes in place to ensure that. As for maps, most councils have published coverage maps with our support. More detailed data will be released by them in due course once surveys have been completed and we know for sure that we are going to an area."
Communications minister Ed Vaizey highlighted that the regulator Ofcom had recently ranked the UK's provision of broadband ahead of other countries.
"Britain has the best superfast broadband of all five leading European economies," he said.
"The government's nationwide broadband rollout is ahead of schedule; multiple robust safeguards are already in place to ensure value for money, and thousands of homes and businesses up and down the country are already getting the benefits."'Monopoly position'
By 2015, the government will have given a total of £490m in grants to English local authorities and administrations in Scotland, Wales and Northern Ireland to subsidise the infrastructure needed to improve rural broadband.
Its goal is that by 2015 all UK premises can experience at least two megabit per second downloads and that 90% of premises can access "superfast" downloads of at least 20Mbps.
The councils and administrations have to match the cash with their own funds and pick a contractor. The firm then adds cash of its own, which it can later recoup through customer fees.The government wants 90% of buildings to be able to get a minimum download speed of 20Mbps
Nine firms initially showed interest, but the House of Commons Public Accounts Committee (Pac) warned last year that taxpayers faced being "ripped off" after BT won the first 26 bids put out to tender.
Since then BT has secured all of the 18 further contracts offered. The committee said that placed the company in a "monopoly position" meaning officials could never be sure if they had got value for money.
Pac also raised concern that the maps published by local bodies showing where broadband would be offered often lacked detail.
It said this made it hard for other organisations to work out where they could pursue their own independent schemes to fill gaps in BT's coverage or offer faster speeds.
Pac said the government should therefore work "urgently" alongside local bodies to make it possible for homes and businesses to carry out searches based on their full postcodes that revealed whether they were covered and the intended speed of service.
The committee noted it had heard allegations that BT had taken advantage of the "inadequate" information it had originally provided; both to expand into areas that rivals had subsequently shown interest in, and to refuse to boost speeds to at least one village that it declared too expensive to cover after winning a contract.
The Independent Networks Co-operative Association (Inca) - which represents smaller internet providers - has highlighted cases in Wiltshire and Lancashire where it said community schemes had been cancelled or put at risk by BT "overbuilding" its projects.
"Government and local authorities must make sure that alternative schemes, pulling in additional private sector and community funding, are supported not stymied," Inca's chief executive Malcolm Corbett told the BBC.
"Allowing BT to use state funding to undermine competitors is not in the interests of rural communities, nor the UK as a whole."Subject to change
But a spokesman for BT explained any changes in its plans as being the result of the surveys it carried out after being awarded the contracts.
"The fibre broadband programme is constantly evolving, and there is no definitive rollout plan until we complete detailed survey work in each locality," said a spokesman.BT says it cannot confirm which areas will be covered before it wins a contract
"This means that plans will undoubtedly change. For example in Cornwall, we originally said we'd be able to connect 85% of the county, but we now expect to get to around 95-97%.
"That could happen in other areas too, but we can also encounter obstacles in certain locations, like blocked ducts or lack of available power, which makes the cost of deploying fibre prohibitive."
A further £500m of taxpayers' funds has been earmarked to enhance coverage after 2015.
Before that happens Pac has urged the government to analyse and publish details of this round's deployment costs to help local authorities be better informed .
The committee also suggested work be done to address a "lack of competitive tension" in the tendering process.