A group of 21 business figures and politicians has called for the proposed high-speed rail link between London and Birmingham to be scrapped.
In an open letter, the group calls the plan an "expensive white elephant", and a "vanity project".
Transport Secretary Philip Hammond says the £17bn project will deliver major strategic benefits to the economy and other business leaders have backed it.
Work on the line is due to start in 2015, if the route is approved.
A public consultation began last month on the proposed location of the new track in the Chilterns, Buckinghamshire and Warwickshire.
Expensive 'train set'
The project, known as HS2, is designed to shorten journey times between London and Birmingham, before connecting to Manchester and Leeds.
In total, it will cost an estimated £32bn.
But in their letter to the Daily Telegraph, the business leaders say "an extremely expensive white elephant isn't what the economy needs".
"If the government want to encourage growth there are better ways to get Britain growing and make us more competitive than getting each family to pay over £1,000 for a vanity project that we cannot afford," it says.
The letter is signed by 21 business leaders, politicians and economists including the former Chancellor, Lord Lawson, and Lord Wolfson, the chief executive of Next.
'Heads in the sand'
It dismisses HS2 as a "train set" which will be used only by a minority.
"There are better options to increase capacity more affordably and reduce overcrowding more quickly than HS2, which will take decades to complete," argues the letter.
"Stretched commuter trains and congested roads are a bigger issue than the journey time to London."
Philip Hammond disagrees with the assessment. He argues that high-speed rail will bring major strategic benefits.
In a statement, Mr Hammond said: "Sticking our heads in the sand, as these people seem to wish, is simply not an option."
He called high-speed rail a "once-in-a-generation opportunity to transform the way we travel in the 21st Century".
Dozens of business leaders, including CBI director general John Cridland and former British Airways chief executive Willie Walsh, have backed HS2.
Friends of the Earth said the plan would do little to cut carbon emissions.
Transport campaigner Richard Dyer said: "The billions of pounds earmarked for high-speed rail would be better spent making our existing overcrowded rail network cheaper and more attractive than driving or taking a short-haul flight."
The public consultation on the route will last until 29 July.
If the plans go ahead, the government expects the line to the West Midlands to be finished by 2026, with the links to Manchester and Leeds completed in 2032-33.