Those in charge of the HS2 project have been been accused of "fiddling the figures" by the deputy chairman of the project's review panel.
Parliament was "seriously misled" over the costs of HS2, which would be poor value for money and bad for the environment, the former Labour transport spokesman Lord Berkeley has said.
He also accused the project of being "completely out of control financially".
Lord Berkeley found that there is “overwhelming evidence” that costs for the high-speed railway are “out of control”, according to the Sunday Telegraph, which has seen the report submitted to Prime Minister Boris Johnson.
A HS2 Ltd spokesperson said there have been many individual views expressed about the HS2 project, of which Lord Berkeley's is just one.
His comments come after his hard-hitting 70-page dissenting report into the high speed rail proposal was published, listing several grave concerns. Chief among them is the blow-out of estimated costs.
The network was initially expected to cost £50.1 billion. Latest estimates by HS2 Ltd - the private company in charge of the project - put the price at £88 billion.
But Lord Berkeley says independent analysis arrives at a figure of at least £107.92 billion.
"It's an enormous figure and Parliament should have had an opportunity to debate this.
"This project is probably two or three times over budget even before the construction has started," Lord Berkeley told Sky's Sophy Ridge On Sunday.
He added: "For me, HS2, if it were almost cancelled except for the bit in the Northern Powerhouse area and replaced by about half the investment on local services, local rail network in the north and the Midlands, it would be much better for everybody who lives up there.
Responding to Lord Berkeley's comments, Director of the Northern Powerhouse project Henri Murison said they "sound like the views of someone who has always been a sceptic of HS2 simply making the points they've made before".
He added: "He accused the Government and others of misleading Parliament which is wrong, but he also gets the numbers wrong."
Regional transport organisation Midlands Connect criticised the Labour peer's report.
Director Maria Machancoses said: "Lord Berkeley's suggestion that the Government should consider building only small sections of HS2 in the north of England shows a disgraceful ignorance of how important the scheme is to the Midlands.
"Contrary to Lord Berkeley's view that the benefits of HS2 have been overstated, I believe firmly that they have been vastly underestimated."
What is in the report?
Lord Berkeley says he believes “that Parliament was misled on the question of HS2 costs” from the evidence he has seen, adding it is “highly unlikely” the legislation would have passed if it had been given the “real costs figures by the Department of Transport”.
The deputy chairman launched a scathing attack on the Government-commissioned review in November, after a leaked draft recommended that the high-speed railway should be built in full despite soaring costs.
Lord Berkeley concluded HS2 was "the wrong and expensive solution" to providing better North-South intercity services, adding that it would be "poor value for money".
In the report revealed by the Telegraph, Lord Berkeley accuses HS2 Ltd of a lack of co-operation with the review panel.
What has been the reaction from HS2 Ltd and the Department for Transport?
Phase one of HS2 is planned to run between London and Birmingham.
It was initially planned to launch in 2026, but a recent report by HS2 Ltd stated that this could be pushed back until 2031
An HS2 Ltd spokesman said: “There have been many individual views expressed about the HS2 project, however we await the publication of the Government’s official review.
“HS2 Ltd has provided full co-operation to Mr Oakervee and his review team, and if the Government decides to proceed we have a highly skilled team in place ready to build Britain’s new railway.
“Investment in a state-of-the-art high speed line is critical for the UK’s low-carbon transport future, will provide much needed rail capacity up and down the country, and is integral to rail projects in the North and Midlands which will help rebalance the UK economy.”
The Department for Transport last night said Lord Berkeley’s report represented his own view only.
“The Government commissioned the Oakervee review to provide advice on how and whether to proceed with HS2, with an independent panel representing a range of viewpoints,” a DfT spokesperson said.
“Lord Berkeley’s report represents his personal view.”