A group of academics claim the cost of HS2 is “needlessly” high and have called on the government to rethink the project.
They support the high speed rail link but questioned why it is five-time more expensive than the French equivalent.
The group also questioned the need to run the trains at such high-speeds which will increase costs.
Professor James Croll of University College London, told the BBC: "It is just vanity for the UK to have faster trains than the usual high-speed trains. The UK is far too small geographically to need an ultra-high speed network - by the time the trains get up to speed it will be almost time to slow them down again.
"The decision to design for 400km/h has led to a succession of needlessly expensive knock-on effects in construction which will be saddling taxpayers with huge bills for a generation."
The current HS2 project, which has come under fire from both political sides, would link London to Birmingham by 2026, with tracks to cities in the north of England including Leeds and Manchester, built by 2030.
Once complete, journey times will fall by an hour from London to Manchester, by 53 minutes from London to Glasgow and by 65 minutes from Birmingham Curzon Street to Leeds.
The academics say the fast trains will increase carbon emissions and the extra speed from ultra-fast services requires 23 per cent more energy, but saves just 3.5 minutes from London to Birmingham.
Professor Tony May from Leeds University told the BBC: "What's needed is an independent, objective assessment of the alternatives.
"These would include a less damaging version of HS2, a better-connected new line from London and transport investment in the North rather than to the North.”
HS2 said cost reductions were being examined, and has conducted an investigation.
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