The multi-billion high-speed rail link project is an "expensive white elephant" and should be scrapped, an alliance of business leaders, politicians and economists say.
In a letter to The Daily Telegraph, the 21 signatories dismissed the scheme as an unaffordable "vanity project" that will cost each family over £1,000.
They said it would be wrong to spend in excess of £30million on a “train set that only a minority of fortunate passengers will use”, claiming the money should be pumped into the faltering economy.
The alliance, which includes Lord Wolfson, the chief executive of Next and the Tories' competitiveness adviser and Lord Lawson, a former chancellor, wrote: "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."
The government-planned scheme, known as HS2, will see a new 200mph train line connect London and Birmingham and eventually reach to Leeds and Manchester and Glasgow.
Supporters say the link, which will cut through areas of Buckinghamshire and Warwickshire, will generate "massive economic benefits", but it has faced mass opposition from communities who will be affected by the upheaval.
The group of chief executives, top economists and senior Conservatives said a fast and frequent service to Birmingham and Manchester already existed with trains running at up to 125mph.
They added: "There are better options to increase capacity more affordably and reduce overcrowding more quickly than HS2, which will take decades to complete.
"Stretched commuter trains and congested roads are a bigger issue than the journey time to London."
Other signatories included Matthew Sinclair, director of the TaxPayers' Alliance and Mark Littlewood, the director-General of the Institute of Economic Affairs.
Responding to the letter, Transport Secretary Philip Hammond said: "I understand that this is a controversial project, particularly for many of those who live along the line of the route, but the Government's job is to balance local objections against the national interest. We believe that the best way to create jobs and growth is to invest in Britain's future.
"This is a big project, but the cost will be spread over 15 years and we will generate more than £2 of direct benefits for every £1 of cost - as well as major strategic benefits to the wider economy. That is why so many British businesses have already given our high speed rail (HSR) plans their overwhelming backing."
He went on: "HSR is a once-in-a-generation opportunity to transform the way we travel in the 21st century and would help build a modern economy, fit for the future. Countries across Europe and Asia are already pressing ahead with ambitious plans for HSR. Britain cannot afford to be left behind.
"As any regular rail passenger will tell you, our railways are increasingly crowded, and more and more people are having to stand. We need to invest in new lines and new trains. Sticking our heads in the sand, as these people seem to wish, is simply not an option."
The IET Transport Policy Panel, on behalf of the IET Trustees, intends to submit a response to this consultation and invites comments from members who have expertise in this area and have studied the consultation documents. In its capacity as a professional body, the IET will confine itself to only addressing those questions that are within its area(s) of competence.