Margaret Hodge MP, Chair of the Committee of Public Accounts, has said the economic justification for HS2 is "very questionable".
It comes as the Committee of Public Accounts issued a withering assessment of the HS2 high-speed rail project, warning costs were spiralling whilst benefits were dwindling.
The Transport Secretary, Patrick McLoughlin, said the case for the £50 billion project was "absolutely clear," as rail routes would be "overwhelmed" by rising passenger numbers.
MPs from the Commons public accounts committee have called for the Department of Transport to provide more detailed evidence to support the estimated £50 billion investment. Presenting the committee's findings, chairperson Marget Hodge said:
The pattern so far has been for costs to spiral - from more than £16 billion to £21 billion plus for phase one - and the estimated benefits to dwindle.
In my committee's experience, not allowing enough time for preparation undermines projects from the start.
Transport Secretary Patrick McLoughlin has rejected the findings of the Commons public accounts committee, which criticised the costs and benefits of the HS2 high-speed rail network.
Mr McLoughlin said the case for the £50 billion project was "absolutely clear," as rail routes would be "overwhelmed" by rising passenger numbers. He said:
"The project will free up vital space on our railways for passengers and freight, generate hundreds of thousands of jobs and deliver better connections between our towns and cities.
"HS2 is a vital part of our plan to give Britain the transport infrastructure it needs to compete.
The Commons public accounts committee has issued a withering assessment of the HS2 high-speed rail project, warning costs were spiralling whilst benefits were dwindling.
The committee said the case for the £50 billion project was based on "fragile numbers, out-of-date data and assumptions which do not reflect real life" with no evidence it would aid regional economies not simply "suck" even more activity into London.
It has demanded an urgent explanation of how quickly the Department of Transport could plug the "significant" gaps in the commercial and major project expertise in its teams.
An influential group of MPs says the DfT has failed to present 'a convincing strategic case' for HS2.Read the full story ›
A protest march against the proposed HS2 trainline has been held in South Staffordshire.
People from the Colton and Kings Bromley areas walked ten miles of where the high speed railway line is planned to travel, carrying 73 balloons to represent the estimated £73 billion cost.
John Sadler, from the Kings Bromley Stop HS2 campaign group, said it would cause "devastation" to the countryside.
People in South Staffordshire opposed to the HS2 train line are staging a protest march today.
Villagers from the Colton area, near Rugeley, will be walking a ten mile route carrying 73 balloons, representing the £73 billion figure quoted recently as estimated rail line costs rise.
The same group of protesters recently hired a crane to demonstrate the height of a proposed embankment near to their homes.
World record-setting engine, the Mallard, was the "high point of achievement" for British steam locomotive industry, a campaigner has said.
Henry Cleary, from the Mallard Grantham Partnership, told ITV Central why he felt the Mallard was so special.
World-record setting steam locomotive Mallard is at Grantham Station this weekend as part of the town's Story of Speed festival. It's 50 years since the locomotive was last in the town.
Mallard broke the world record at Stoke Bridge near Grantham in 1938, hitting 125.88 mph, a record which still remains unbroken.
The Midlands town of Grantham in Lincolnshire is expecting thousands of visitors when the fastest ever steam locomotive, Mallard returns to the town after a 50 year absence.
The event is part of the 75th anniversary celebrations of the 126mph speed record set by Mallard just south of Grantham at Stoke Bank on 3, July, 1938.